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PubMed2001

An elevated amniotic fluid matrix metalloproteinase-8 level at the time of mid-trimester genetic amniocentesis is a risk factor for spontaneous preterm delivery.

OBJECTIVE: Strong evidence implicates chronic intra-amniotic inflammation in the etiology of mid-trimester abortion and spontaneous preterm delivery. The purpose of this study was to determine if concentrations of amniotic fluid matrix metalloproteinase-8, and cytokines such as interleukin-6 and angiogenin can identify patients at risk for spontaneous preterm delivery in patients undergoing mid-trimester amniocentesis. STUDY DESIGN: A case-control study was conducted to compare mid-trimester concentrations of amniotic fluid matrix metalloproteinase-8, interleukin-6, and angiogenin in patients who delivered at term and in those who delivered before term. The study included 19 cases with spontaneous preterm delivery and 95 matched controls with normal outcomes. Patients with abnormal fetal karyotypes or major anomalies were excluded. Matrix metalloproteinase-8, interleukin-6, and angiogenin were measured by using specific immunoassays. Mann-Whitney U tests, Fisher exact tests, and receiver-operating characteristic curves were used for statistical analysis. RESULTS: The median amniotic fluid matrix metalloproteinase-8, interleukin-6, and angiogenin concentrations of patients with spontaneous preterm delivery were significantly higher than those of control cases (matrix metalloproteinase-8: median, 3.1 ng/mL [range, 0.3-1954.9 ng/mL] vs median, 1.3 ng/mL [range, <0.3-45.2 ng/mL], P <.01; interleukin-6: median, 0.32 ng/mL [range, 0.04-2.52 ng/mL] vs median, 0.18 ng/mL [range, 0.01-1.81 ng/mL], P <.01; angiogenin: median, 11.1 ng/mL [range, 4.5-30.7 ng/mL] vs median, 6.7 ng/mL [range, 1.3-21.9 ng/mL], P <.001). Amniotic fluid matrix metalloproteinase-8 concentrations higher than 23 ng/mL had the highest specificity and odds ratio (sensitivity, 42% [8/19]; specificity, 99% [94/95]; OR, 68.4 [95% CI, 7.8-599.1]) in the identification of the patients with preterm delivery after genetic amniocentesis. CONCLUSIONS: Elevated mid-trimester concentrations of amniotic fluid matrix metalloproteinase-8, interleukin-6, and angiogenin are a risk factor for early spontaneous preterm delivery (<32 weeks). An elevated matrix metalloproteinase-8 level of >23 ng/mL is a powerful predictor of spontaneous preterm delivery (<32 weeks) with an odds ratio of 68.4. Amniotic fluid studies can be used to improve the risk assessment for preterm delivery in women who undergo mid-trimester amniocentesis for genetic indications.

Adult↗

PubMed2002

How does early ultrasound scan estimation of gestational age lead to higher rates of preterm birth?

OBJECTIVE: Early ultrasound scanning estimation of gestational age is known to increase the reported preterm delivery rate (<37 completed weeks) compared with estimation by date of the last normal menstrual period, but it is unclear how this systematic difference arises. STUDY DESIGN: This study was a hospital-based study of 44,623 women who delivered a live-born or stillborn infant between January 1, 1978, and March 31, 1996, and who had both last normal menstrual period-based and early (usually at 16-18 weeks) ultrasound scan-based gestational age estimates. Cross-classification of the 2 estimates by completed weeks was used to examine the direction and magnitude of the differences between them and to compare the resulting classifications of preterm birth. RESULTS: The early ultrasound scan-based gestational age distribution was shifted uniformly to the left (ie, lower gestational age) relative to the last normal menstrual period gestational age distribution; the early ultrasound scan-based preterm delivery rate was 9.1%, which was 19.5% (n = 659 births) higher than the 7.6% rate by last normal menstrual period (P <.0001). The last normal menstrual period estimate exceeded the early ultrasound scan estimate far more often than the reverse, up to and including early ultrasound scan estimates of 40 weeks. No concentration of 4-week discrepancies was observed in either direction, as would be expected with random or systematic errors in recall of the last normal menstrual period. The absolute number of births at 37 to 39 weeks of gestation (by last normal menstrual period) that were reclassified as preterm (n = 1206 births) was much higher than the number of preterm births at 34 to 36 weeks of gestation that were reclassified as term (n = 581 births). The net increase of 625 preterm births (from 581 to 1206 births) that resulted from reclassification of births at 37 to 39 last normal menstrual period weeks accounted for 95% of the total 659-birth increase in early ultrasound scan-based preterm births at all last normal menstrual period gestational ages. CONCLUSION: Early ultrasound scanning reduces the gestational age estimate across the entire gestational age range; early ultrasound scan-based reclassification of gestational age results in a substantial increase in the prevalence of preterm births. Small downward reclassifications exceed upward reclassifications of similar magnitude, which is consistent with previous reports that delayed (>14 days) ovulation is more frequent than early (<14 days) ovulation.

Adult↗

PubMed2002

Changes in cervical length and the risk of preterm labor.

OBJECTIVE: The purpose of this study was to assess the value of cervical length change as a predictor of preterm labor. STUDY DESIGN: We used an historic cohort of 154 women to compare change in cervical length and preterm birth. Independent variables included cervical length at the first sonogram, absolute change of cervical length, and change per unit time. Covariates included age, parity, and history of preterm birth. Eligible patients had 2 or more sonograms that included cervical length. RESULTS: The risk of preterm delivery increased as the length of the cervix declined, after an adjustment was made for the initial cervical length (P <.05). There were no significant interactions between initial length and the change of length; however, the highest rate of preterm deliveries occurred among women with a cervical length <3 cm at the first sonogram (23%). If the change in cervical length was expressed as a unit equal to a decline of 1 cm per month, the odds of giving birth to a preterm baby were 6.8-fold greater per unit change (P <.05). CONCLUSION: A cervical length of <3 cm before 16 weeks of gestation is associated strongly with preterm birth; independently of baseline length, more rapid shortening of the cervix increases the risk of preterm birth.

Cervix Uteri↗

PubMed2002

Sexual intercourse association with asymptomatic bacterial vaginosis and Trichomonas vaginalis treatment in relationship to preterm birth.

OBJECTIVE: The purpose of this study was to determine whether sexual intercourse was associated with the treatment efficacy or the incidence of preterm birth in two large randomized trials in which metronidazole treatment of bacterial vaginosis or Trichomonas vaginalis did not reduce preterm birth. STUDY DESIGN: Secondary analysis of two multicenter, double-blind, placebo-controlled trials in which women with asymptomatic bacterial vaginosis on Gram stain or asymptomatic T vaginalis on culture were randomized at 16 to 23 weeks of gestation to metronidazole or placebo. In both studies, women took 2 g of metronidazole or placebo in the presence of a nurse (first dose) and were given a second dose to take 48 hours later. This regimen was repeated (third and fourth doses) at 24 to 29 weeks. At the time of the third dose, bacterial vaginosis and T vaginalis specimens were collected again. Patients who were randomly selected to receive metronidazole were analyzed for bacterial vaginosis and T vaginalis at 24 to 29 weeks and for preterm birth of <37 weeks of gestation, according to intercourse between first and second doses and between the second and third doses. Continuous variables were compared with the use of the Wilcoxon rank-sum test; categoric variables were compared with the use of the chi(2 ) test, Fisher exact test, or the Mantel-Haenzel test of trend. RESULTS: Sexual intercourse between the first and second doses or between the second and third doses did not influence the incidence of bacterial vaginosis (18% vs 24%; relative risk, 0.7; 95% CI, 0.5-1.1; and 23% vs 20%; relative risk, 1.2; 95% CI, 0.9-1.6, respectively) or T vaginalis (4% vs 8%; relative risk, 0.5; 95% CI, 0.1-3.6; and 5% vs 10%; relative risk, 0.5; 95% CI, 0.2-1.1; respectively) at 24 to 29 weeks of gestation compared with no intercourse. In the T vaginalis trial, sexual intercourse between the first and second doses or between the second and third doses did not influence the incidence of preterm birth (13% vs 17%; relative risk, 0.8; 95% CI, 0.3-2.1; and 16% vs 17%; relative risk, 1.0; 95% CI, 0.6-1.6; respectively) compared with no intercourse. In the bacterial vaginosis trial, although sexual intercourse between the first and second doses did not influence the incidence of preterm birth (11% vs 12%; relative risk, 0.9; 95 % CI, 0.6-1.5), sexual intercourse between the second and third doses was associated with a reduction in the incidence of preterm birth (10% vs 16%; relative risk, 0.6; 95% CI, 0.4-0.9) compared with no intercourse. CONCLUSION: Sexual intercourse was associated with neither the efficacy of metronidazole treatment of bacterial vaginosis or T vaginalis nor with the incidence of preterm birth. In the bacterial vaginosis study, intercourse between the second and third doses had a negative association with preterm birth.

Black or African American↗

PubMed2002

The impact of prenatal care in the United States on preterm births in the presence and absence of antenatal high-risk conditions.

OBJECTIVE: This study was undertaken to determine the association between prenatal care in the United States and preterm birth rate in the presence, as well as absence, of high-risk pregnancy conditions for African American and white women. STUDY DESIGN: Data were derived from the natality data set for the years 1995 to 1998 provided by the National Center for Health Statistics. Analyses were restricted to singleton live births that occurred at >/=20 weeks' gestation. Multiple births, fetal deaths, congenital malformations, chromosomal abnormalities, missing data on gestational age, and birth weight less than 500 g were excluded. Multivariable logistic regression analyses were used to adjust for the presence or absence of various antenatal high-risk conditions, maternal age, gravidity, marital status, smoking, alcohol, and education. Prenatal care was considered present if there was one or more prenatal visits. Preterm delivery was defined as delivery at less than 37 completed weeks of gestation. RESULTS: For 14,071,757 births analyzed, 1,348,643 (9.6%) resulted in preterm birth. Preterm birth rates were higher for African American women than white women in the presence (15.1% vs 8.3%) and absence (34.9% vs 21.9%) of prenatal care. The absence of prenatal care increased the relative risk for preterm birth 2.8-fold in both African American and white women. There was an inverse dose-response relationship between the number of prenatal visits and the gestational age at delivery both among African American and white women. Lack of prenatal care was associated with increased preterm birth rates to a similar degree in the presence of pregnancy complications for both African American and white women, ranging from 1.6-fold to 5.5-fold for the various antenatal high-risk conditions. CONCLUSION: In the United States, prenatal care is associated with fewer preterm births in the presence, as well as absence of high-risk conditions for both African American and white women. Strategies to increase prenatal care participation may decrease preterm birth rates.

Black or African American↗

PubMed2001

Development of left ventricular systolic and diastolic function in preterm infants during the first month of life: a prospective follow-up study.

OBJECTIVES: We studied the left ventricular systolic and diastolic function in preterm infants during the first month of life in comparison with the respective patterns in term neonates. STUDY DESIGN: Serial 2-dimensional/M-mode and Doppler transmitral flow velocity measurements were performed in 20 preterm (gestational age, 32 to 36 weeks) and 25 term infants between days 2 and 5 after birth and at age 1 month. RESULTS: After birth, the early velocity, early integral, early filling fraction, early and atrial velocity ratios, and early and atrial integral ratios were lower in the preterm than in the term infants (P <.01). During the first 4 weeks of life, these values, the atrial velocity, and the atrial integral increased gradually, whereas the atrial filling fraction, diastolic filling time, and deceleration time of early diastolic filling decreased slightly with postnatal age (P <.01) in the preterm infants. At age 1 month their diastolic function reached the level of term infants with the exception of early and atrial integral ratios and atrial filling fraction. The measures of systolic performance were within normal range, but midwall fractional shortening at 2 to 5 days (P <.05), and fractional shortening area (P <.05), as well as midwall fractional shortening (P <.01) at 1 month of age, were slightly inferior in the preterm than in the term infants. During the first month the left ventricular mass and left ventricular mass/body surface area ratio increased more markedly in the preterm than term infants, significantly in both groups (P <.05). CONCLUSIONS: The preterm diastolic patterns represent a transition between the patterns of the fetus and those of term neonates. These changes reflect an improvement in the left ventricular diastolic function, more markedly in relaxation than in compliance. The postnatal increase in the transmitral measures and left ventricular mass suggest marked myocardial adaptation to the extrauterine environment in the preterm infant already during the first month.

Blood Flow Velocity↗

PubMed2003

The impact of prenatal care on preterm births among twin gestations in the United States, 1989-2000.

OBJECTIVE: The purpose of this study was to determine the association between prenatal care and preterm births among twin gestations in the presence and absence of high-risk pregnancy conditions. STUDY DESIGN: Twin birth data in the United States were used to determine the association between preterm birth and prenatal care with the use of logistic regression. RESULTS: Of the 779,387 twin births, 54.7% twin births were delivered preterm. The rate was higher among black women than among white women in the presence (57.0% vs 51.2%, respectively) and absence (70.3% vs 61.6%, respectively) of prenatal care. The absence of prenatal care increased the relative risk for preterm birth by 1.24-fold among black women and by 1.22-fold among white women. Lack of prenatal care was associated with increased preterm birth rates in the presence of most high-risk conditions. CONCLUSION: Prenatal care is associated with fewer twin preterm births in the presence and absence of high-risk conditions. Increased prenatal care participation may help decrease preterm birth rates and also narrow the black-white twin preterm birth disparity.

Black People↗

PubMed2005

Is older maternal age a risk factor for preterm birth and fetal growth restriction? A systematic review.

To determine if there was an association between advancing maternal age and adverse pregnancy outcomes (preterm delivery and small-for-gestational-age births), a systematic review was conducted based on a comprehensive search of the literature from 1985 to 2002. Ten studies met the following inclusion criteria: (1) assessed risk factors for preterm birth by subtype (i.e., idiopathic preterm labor, preterm premature rupture of membranes) and small-for-gestational-age (SGA) birth (fetal growth restriction); (2) used acceptable definitions of these outcomes; (3) were published between January 1985 and December 2002; (4) were restricted to studies that have considered preterm birth due to idiopathic preterm labor or premature rupture of membranes or both; (5) were restricted to singleton live births; (6) were conducted in a developed country; and (7) were published in English. The majority of the studies reviewed found that older maternal age was associated with preterm birth. There is insufficient evidence to determine if older maternal age is an independent and direct risk factor for preterm birth and SGA birth, or a risk marker that exerts its influence on gestational age or birth weight or both through its association with age-dependent confounders. Future research is needed to quantify the independent and unconfounded impact of delayed childbearing on neonatal outcomes, as well as to identify the pathways involved.

Adult↗

PubMed2002

Cerebral palsy in preterm infants: a population-based case-control study of antenatal and intrapartal risk factors.

UNLABELLED: Previous studies have indicated that foetomaternal infection increases the risk of spastic cerebral palsy (CP) in term infants, whereas this association appears to be less evident in preterm infants. The aim of this study was to analyse infection-related risk factors for spastic CP in preterm infants. A population-based series of preterm infants with spastic CP, 91 very preterm (<32 wk) and 57 moderately preterm (32-36 wk), born in 1983-90, were included and matched with a control group (n = 296). In total, 154 maternal, antenatal and intrapartal variables were retrieved from obstetric records. In the entire group, histological chorioamnionitis/pyelonephritis, long interval between rupture of membranes and birth, admission-delivery interval <4 h and Apgar scores of <7 at 1 min just significantly increased the risk of CP, and Apgar scores of <7 at 5 and 10 min were strongly associated with an increased risk. Abruptio placentae, Apgar scores <7 at 1 min and pathological non-stress test (reason for delivery) were significant risk factors of CP only in the moderately preterm and hemiplegic groups, whereas fever before delivery was a significant risk factor in the very preterm and spastic diplegic groups. Antibiotics during pregnancy was associated with CP only in the spastic diplegic CP group. CONCLUSION: Antenatal infections marginally increased the risk of CP. Low Apgar score and abruptio placentae were associated with CP, especially in moderately preterm infants with hemiplegic CP.

Apgar Score↗

PubMed2001

Linguistic skills in relation to neurological findings at 8 years of age in children born preterm.

The linguistic skills of 8-year-old children born preterm (n = 42) with birthweight < 1750 grams from a 1-year birth cohort for 1985-86 in northern Finland were studied with three different language tests, namely the Illinois Test of Psycholinguistic Abilities (ITPA), the Token Test for Children (TTC) and the Morphological Test (MT) for Finnish children. Full-term control children (n = 42) with birthweight > or = 2500 grams from the same birth cohort were matched individually with their preterm pairs for age, sex, twinship, mother's education, place of residence, birth order and family type. The preterm children's language abilities were studied in relation to their neurological status and to the periventricular leukomalacia (PVL) findings of magnetic resonance imaging (MRI). The preterm children with minor neurodevelopmental dysfunctions (MND) scored worst and differed significantly from their matched controls in TTC. They also differed significantly from other preterm subgroups, namely healthy preterm and preterm children with cerebral palsy (CP), in verbal comprehension measured by TTC. PVL findings were not associated with performance in the language ability tests. A closer and regular follow-up of language development in the MND-disabled group among the low-birthweight preterm children is recommended.

Child↗

PubMed2006

Neighborhood deprivation and preterm birth in Plymouth, UK.

OBJECTIVE: To assess the relationship between neighborhood deprivation and the preterm birth rate in Plymouth, UK, using routinely collected data from a clinical information system. METHODS: We used a clinic-based prospective case register study of all births in Plymouth UK between 1 January 1996 and 31 December 1997 combined with indices of neighborhood deprivation to assess the relationship between neighborhood deprivation and the preterm birth rate. Areas (n = 43) were classified according to the Townsend index, measuring material deprivation. Preterm births were compared with term births. RESULTS: The incidence of singleton preterm birth was 5.3% (95% confidence interval (CI) 4.6, 6.0). The singleton preterm birth rate increased with Townsend material deprivation score. Crude rates increased by 31% (relative risk (RR) (95% CI) 1.31 (0.94, 1.84), p = 0.056) among those living in the most deprived areas compared to those living in the least deprived areas. A stepwise binary logistic regression model showed an increase in the relative risk of preterm birth of 7% for every unit increase in the Townsend material deprivation score (RR (95% CI) 1.07 (1.03, 1.11)). CONCLUSION: Neighborhood deprivation is related to preterm birth. Examining individual and neighborhood factors together may increase understanding of the complex causes of preterm birth.

Adolescent↗

PubMed2003

Matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 in plasma/serum and urine of women during term and threatened preterm labor: a clinical approach.

OBJECTIVE: To explore the concentrations of matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1) in plasma, serum and urine of women during term and threatened preterm labor. METHODS: Plasma and urine proMMP-9 as well as serum and urine TIMP-1 were evaluated in 60 healthy pregnant women; 20 of them presented in term labor following an uncomplicated pregnancy, 20 of them presented with threatened preterm labor and intact membranes at 24-36 gestational weeks and 20 of them were at 24-40 gestational weeks with no evidence of uterine contractions or other pregnancy complications. Data were analyzed with non-parametric statistical tests and cut-off values were determined with receiver operator characteristic curves. RESULTS: ProMMP-9 values were significantly higher and TIMP-1 values were significantly lower in cases with uterine term or preterm contractions compared to non-labor status; and in cases with preterm contractions that progressed to true preterm labor compared to those in which contractions were arrested. CONCLUSIONS: Alterations in the concentrations of proMMP-9 and TIMP-1 can be detected in plasma or serum and urine of pregnant women experiencing term or preterm uterine contractions. The altered values of proMMP-9 and TIMP-1 could possibly identify the inevitable progress of preterm contractions to true preterm labor.

Adult↗

PubMed2004

Actigraphic monitoring of the activity-rest behavior of preterm and full-term infants at 20 months of age.

Differences in the activity-rest behavior of preterm and full-term infants provide an important contribution to the analysis of the ontogeny of circadian rhythms. In this study, we recorded the activity-rest behavior of 17 preterm and 8 full-term infants at the approximate age of 20 months over an average of 10 days by means of actigraphic monitoring (Actiwatch, Cambridge Neurotechnology Ltd.). At the same time, the parents of the infants kept a daily diary. The activity-rest rhythm, the nighttime sleep duration, the daytime rest duration, as well as the sleep quality of the infants were analyzed. Preterm and full-term infants at the age of 20 months show a circadian rhythm with a period length between 23 h 32 min (23:32 h) and 24 h 23 min (24:23 h). It can be concluded that the preterm and full-term infants all reached a vital developmental step by showing the dominant circadian rhythm in the spectrum. The daytime rest duration of preterm infants is significantly shorter than that of full-term infants. The sleep quality of preterm infants is significantly lower than that of full-term infants, which means that the preterm infants have a larger percentage of less restful nighttime sleep. In other studies preterm infants show an over-proportional frequency of attention deficit hyperactivity disorder (ADHD). For this reason, future analyses should reveal whether or not actigraphic monitoring is a suitable means for an early identification of activity-rest behavior in children who may develop ADHD.

Activity Cycles↗

PubMed2005

The thyroid and pregnancy: a novel risk factor for very preterm delivery.

The major cause of neonatal mortality and morbidity is preterm delivery in general (< 37 completed weeks), and especially very preterm delivery (< 32 completed weeks). The objective of this study is to determine if either thyroid hormonal dysfunction and/or the presence of thyroid autoantibodies in the mother are associated with an increased risk of preterm and/or very preterm delivery. Data were collected prospectively and analyzed as a nested-case control study. There were 953 delivered gravidas enrolled between 1996 and 2002. Samples were collected at entry to care and stored at -70 degrees C. Cases included all women with preterm delivery (n = 124). Controls (n = 124) were randomly selected from among the 829 women who delivered at term (> 37 completed weeks). All samples were assessed for thyroid stimulating hormone, thyroperoxidase antibody, and thyroglobulin antibody. Gravidas with high thyrotropin (TSH) levels had a greater than threefold increase in risk of very preterm delivery. In some analyses, gravidas who tested positive for thyroglobulin antibody at entry to prenatal care also had a better than twofold increased risk of very preterm delivery. There were no significant associations between TSH level or thyroglobulin antibody positivity and the risk of moderately preterm delivery.

Adult↗

PubMed1996

Intrauterine elimination of pyridoxal 5'-phosphate in full-term and preterm infants.

This study addressed the intrauterine elimination of pyridoxal 5'-phosphate (PLP) in 15 preterm and 31 full-term infants, thereby providing estimates of fetal vitamin consumption as well as maternal vitamin requirements during pregnancy. Elimination was calculated as the difference in the plasma PLP concentration between umbilical vein and umbilical artery times the umbilical plasma flow. Plasma flow in the umbilical vein was calculated from pulsed Doppler ultrasonographic determination of blood flow and from the hematocrit value. Plasma PLP concentrations were assayed in maternal and umbilical veins and the umbilical artery; PLP concentrations were similar in preterm and full-term infants (P > 0.05). In both groups of infants the PLP concentration in the umbilical vein (preterm: 100.3 nmol/L; full-term: 63.9 nmol/L) was ninefold higher than in maternal circulation (P < 0.001). In full-term infants, PLP concentrations in maternal and umbilical veins correlated weakly (r = 0.358, P < 0.05), but no significant correlation was found in the preterm group (P > 0.05). The arteriovenous concentration gradient of PLP in cord vessels was higher in preterm infants (15.0 nmol/L) than in full-term infants (2.1 nmol/L), but the difference between groups was not significant (P > 0.05). Preterm infants eliminated 1.7 nmol PLP.kg-1.min-1 in utero, whereas full-term infants eliminated 0.2 nmol PLP.kg-1.min-1 (P < 0.05). The significantly higher plasma flow in preterm infants (116 mL.min-1.kg-1) compared with full-term infants (78 mL.min-1.kg-1) contributed to the higher PLP elimination in preterm infants.

Adult↗

PubMed2004

Preterm delivery rates in North Carolina: are they really declining among non-Hispanic African Americans?

The preterm delivery rate in North Carolina is consistently higher than the national average. However, recent reports suggest that singleton preterm delivery rates for non-Hispanic Whites are increasing while those for non-Hispanic African Americans are decreasing. To study this pattern further, the authors examined data on singleton non-Hispanic White and non-Hispanic African-American births in 1989 and 1999 by using North Carolina vital statistics data. They found that the frequency of preterm delivery rose 1.1% (8.5% to 9.6%) among non-Hispanic Whites but declined 1.4% (17.9% to 16.5%) among non-Hispanic African Americans over the same time period. For both subgroups, a bimodal distribution of birth weights was apparent among preterm births at 28-31 weeks of gestation. The second peak with its cluster of normal-weight infants was more prominent among non-Hispanic African Americans in 1989 than in 1999. To reduce the potential for bias due to misclassification of infant gestational age, frequencies of preterm delivery of infants who weighed less than 2,500 g were calculated. Unlike the original analysis, this calculation showed that preterm delivery increased for both subgroups. A number of non-Hispanic African-American births classified as preterm were apparently term births mistakenly assigned short gestational ages. Such misclassification was more frequent in 1989 than in 1999, inflating 1989 preterm delivery rates.

Adult↗

PubMed2004

Corpus callosum size and very preterm birth: relationship to neuropsychological outcome.

Thinning of the corpus callosum (CC) is often observed in individuals who were born very preterm. Damage to the CC during neurodevelopment may be associated with poor neuropsychological performance. This study aimed to explore any evidence of CC pathology in adolescents aged 14-15 years who were born very preterm, and to investigate the relationship between CC areas and verbal skills. Seventy-two individuals born before 33 weeks of gestation and 51 age- and sex-matched full-term controls received structural MRI and neuropsychological assessment. Total CC area in very preterm adolescents was 7.5% smaller than in controls, after adjusting for total white matter volume (P = 0.015). The absolute size of callosal subregions differed between preterm and full-term adolescents: preterm individuals had a 14.7% decrease in posterior (P < 0.0001) and an 11.6% decrease in mid-posterior CC quarters (P = 0.029). Preterm individuals who had experienced periventricular haemorrhage and ventricular dilatation in the neonatal period showed the greatest decrease in CC area. In very preterm boys only, verbal IQ and verbal fluency scores were positively associated with total mid-sagittal CC size and mid-posterior surface area. These results suggest that very preterm birth adversely affects the development of the CC, particularly its posterior quarter, and this impairs verbal skills in boys.

Adolescent↗

PubMed2002

Fetal sex and preterm birth: are males at greater risk?

BACKGROUND: The existence of a male excess among preterm births is interesting because it could shed light on the aetiology of preterm birth. Possible mechanisms are greater body weight, increased susceptibility to complications of pregnancy, sex-linked biochemical processes and earlier conception in the fertile cycle. METHODS: We measured the association between fetal sex and preterm birth in four original datasets, including a cohort of births after IVF, and 20 populations extracted from published birthweight references. The original samples were also analysed by mode of onset. RESULTS: There were more males among preterm and early preterm births than among term births in most populations, including IVF births (odds ratio: 1.09-1.24). No male excess was observed for two cohorts of black births, induced preterm births in the general population, and spontaneous onset births after IVF. CONCLUSIONS: The proportion of male births declines with increasing gestation, even when time of conception is known. This male excess appears to be strongest for spontaneous preterm births. Studying the sex ratio of preterm births by medical risk factors may clarify why the male excess is absent in some populations. The possibility that obstetric decision-making affects the sex ratio of indicated births must be considered.

Birth Weight↗