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Greg R Alexander

Publications and source records attributed to Greg R Alexander.

At least 37 records · Page 2Linked to original sources
PubMed2005

Smoking-associated fetal morbidity among older gravidas: a population study.

BACKGROUND: We set out to assess the influence of advanced maternal age on fetal morbidity associated with smoking during pregnancy in a population-based retrospective study of 7 792 990 singleton live births between 1995 and 1997 in the United States with documented maternal smoking habit. METHODS: The study group consisted of infants born to mothers aged>or=40 years (older mothers). Two maternal age categories (20-29, "younger mothers"; 30-39, "mature mothers") were constructed as comparison groups. Adjusted odds ratios (ORs) generated from logistic regression models were used to compare fetal morbidity indices associated with smoking across maternal age categories. Main outcome measures included preterm, very preterm, and small for gestational age (SGA). RESULTS: The prevalence of smoking was 13.1%, and decreased with increasing maternal age. Regardless of maternal age, the risk for fetal morbidity was significantly elevated if the mother smoked. The risks for preterm and SGA associated with smoking were significantly higher among older gravidas as compared to younger mothers while mature mothers had risk estimates comparable to those of older mothers. Among smoking mothers only, the risk pattern for fetal morbidity was J-shaped, with babies of older smokers having significantly higher fetal morbidity indices, while those of mature smokers showed lower levels of risk as compared to younger mothers. CONCLUSION: In an era of relatively lower prevalence of smoking during pregnancy, advanced maternal age still increases the risk of smoking-associated fetal morbidity. Our findings reveal new information of elevated risk for very preterm births among older smoking mothers.

Adult↗
PubMed2005

Significant paternal contribution to the risk of small for gestational age.

OBJECTIVE: The aim of this study is to investigate both maternal and paternal contributions in the familial aggregation of small for gestational age. DESIGN: Nested case-control study. SETTING: Metropolitan area of Haguenau, France. POPULATION: Data were drawn from a French population-based maternity registry. After selection, 256 cases born either small for gestational age or average for gestational age were included. METHODS: Controlling for known pregnancy-related risk factors, logistic regression models were used to determine the risk of the child being small for gestational age, given that the mother, father or both were small for gestational age, and to examine interactions between maternal small for gestational age and pregnancy risk factors. MAIN OUTCOME MEASURES: Specifically, we investigate to what extent having either or both parents born small for gestational age increases the risk of small for gestational age in their offspring, after controlling for the established risk factors of small for gestational age and maternal and paternal characteristics. We also explore the extent to which the intergenerational predictors of small for gestational age may modify the effect of current pregnancy-related risk factors. RESULTS: The risk of a small for gestational age offspring was 4.7 times greater for mothers and 3.5 times greater for fathers who were small for gestational age, compared with average for gestational age counterparts. Furthermore, the risk of a small for gestational age offspring was 16.3 times greater when both parents were small for gestational age. No significant interactions between maternal small for gestational age and maternal smoking, hypertension or parity were observed. CONCLUSION: These results indicate that small for gestational age in both mother and father significantly influences the risk of their offspring being small for gestational age. While previous research has indicated that the birth outcome of the mother is an important determinant of the birth outcome of her offspring, these data indicate that the birth outcome of the father plays an equally critical role in determining fetal growth, strongly suggesting a genetic component in the familial aggregation of small for gestational age.

Birth Weight↗
PubMed2005

Influence of nativity on neonatal survival of Black twins in the United States.

OBJECTIVE: To determine the association between maternal nativity and neonatal survival of twins among Black mothers. METHODS: We conducted a retrospective cohort study of twin live births to Black mothers in the United States from 1995 through 1998. We compared levels of overall, early, and late neonatal mortality between twins of US-born and those of foreign-born Black mothers by using hazard ratios generated from a Cox Proportional Hazards Regression model. We adjusted for dependence of observations within twin clusters by means of the Robust Sandwich Estimator. RESULTS: A total of 70,884 individual twin live births to US-born (64,035) and foreign-born (6,849) mothers were analyzed. Twins of US-born mothers had a 23% higher likelihood of dying within the neonatal period compared to those of foreign-born mothers (hazard ratio [HR]=1.23; 95% confidence interval [CI]=1.04-1.46). The disparity in neonatal demise occurred exclusively in the early neonatal period (HR=1.29; 95% CI, 1.06-1.50), with mortality indices comparable in the late neonatal period (HR=0.96; 95% CI, 0.68-1.35). Low and very low birth weight (P<.0001), preterm and very preterm (P<.0001), and small-for-gestational-age neonates (P<.0001) were more prevalent among twins of US-born mothers. CONCLUSIONS: Compared to those of foreign-born, twins of US-born Black mothers experienced higher mortality in the neonatal period. The mortality disadvantage resulted mainly from lower gestational age at birth and the preponderance of small-for-gestational-age babies among US-born Black mothers.

Adult↗
PubMed2005

Advanced maternal age and fetal growth inhibition in triplets.

OBJECTIVE: To determine whether advanced maternal age is associated withfetal growth inhibition in triplets. STUDY DESIGN: We conducted a retrospective cohort study on triplet live births in the United States from 1995 through 1998. The outcomes of fetal growth inhibition measured were low birth weight, very low birth weight, preterm birth, very preterm birth and smallnessfor gestational age. We generated adjusted ORs after taking into account intracluster correlations using the generalized estimating equation framework. RESULTS: As compared to women of younger maternal age (20-29), mature (30-39) and older women (> or =40 years) with triplet gestations tended to have a lower likelihood offetal growth inhibition. Mean birth weight and mean gestational age at delivery increased with increasing maternal age in a dose-dependent pattern (p for trend < 0.0001). As compared to triplets born to younger mothers, those of older women were less likely to have low birth weight (OR=0.51, 95% CI=0.37-0.69) or very low birth weight (OR = 0.58, 95% CI = 0.47-0.72) or to be preterm (OR = 0.39, 95% CI = 0.27-0.56) or very preterm (OR = 0.67, 95% CI = 0.55-0.80). The riskfor small-for-gestational-age infants was comparable. CONCLUSION: Older maternal age is associated with morefavorable triplet fetal growth parameters, although the exact mechanisms of this paradox remain poorly understood.

Adult↗
PubMed2004

Premature rupture of membranes and early mortality among triplets in the United States.

OBJECTIVES: We investigated the relationship between premature rupture of the membranes (PROM) and early mortality among triplets in the United States. STUDY DESIGN: Analysis was conducted on matched and linked triplet sets born to mothers in the United States between 1995 and 1997. The generalized estimating equation framework was used to generate odds ratios after capturing the effects of sibling correlations within triplet clusters. RESULTS: Triplets exposed to PROM were twice as likely to experience stillbirth (OR=2.17, 95% CI [1.26-3.41]), neonatal death (OR=2.23, 95% CI [1.70-3.0]) and infant death (OR=2.21, 95% CI [1.72-2.85]), as compared to those who did not. The population-attributable risk for early mortality due to PROM was 11-12%. CONCLUSIONS: Triplets associated with PROM had a significantly higher level of early mortality than those without. Assuming a causal relationship, 11-12% of all early deaths among triplets in the United States are accounted for by PROM.

Adult↗
PubMed2004

Early mortality among triplets in the United States: black-white disparity.

OBJECTIVE: In this study, we sought to estimate the black-white gap in early mortality among triplets. STUDY DESIGN: This was a retrospective cohort study on triplets delivered in the United States from 1995 to 1997. We computed relative risks for early mortality among triplets born to black mothers using the generalized estimating equation framework. RESULTS: There were 1317 black and 14,364 white triplets analyzed. Black triplets were twice as likely to have neonatal and infant mortality compared with whites (Odds ratio [OR], 2.00, 95% CI, 1.38-2.77; and OR, 2.20, 95% CI, 1.59-3.00, respectively). The widest disparity was observed postneonatally, with black triplets sustaining a level of risk almost 4-fold that of whites (OR, 3.60, 95% CI, 2.10-6.10). Stillbirth and perinatal mortality were comparable for both races. CONCLUSION: Black-white disparity for early mortality among triplets was widest postneonatally. This finding bears important clinical and public health implications.

Adult↗
PubMed2004

Effect of advanced maternal age on early mortality among quadruplets and quintuplets.

OBJECTIVE: This study was undertaken to determine whether advanced maternal age has an impact on survival among quadruplets and quintuplets. STUDY DESIGN: A retrospective cohort study was performed on 1 448 quadruplets and 180 quintuplets delivered in the United States between 1995 and 1997. Infants of older mothers (> or =35 years old) were compared with those of younger ones (<35 years old) in terms of early mortality indices. Adjusted mortality probabilities were computed by yearly intervals of maternal age. RESULTS: The likelihood for neonatal (odds ratio [OR]=2.00, 95% CI=1.20-3.45), perinatal (OR=2.10, 95% CI=1.32-3.23), and infant mortality (OR=2.13, 95% CI=1.28-3.60) was significantly higher among younger mothers. For each unit decrease in maternal age, the odds of stillbirth, neonatal, perinatal, and infant death went up by 9%, 12%, 13%, and 12%, respectively, in a dose-dependent fashion (P for trend <.0001). CONCLUSION: We found increasing maternal age to be associated with favorable survival outcomes among quadruplets and quintuplets.

Adult↗
PubMed2004

The association of parity with mortality outcomes among triplets.

OBJECTIVE: The purpose of this study was to evaluate the association of parity with stillbirth and neonatal and infant death among triplets. STUDY DESIGN: This was a retrospective cohort study of 15,930 triplets who were delivered in the United States between 1995 and 1997. Infants of nulliparous mothers were compared with infants of multiparous mothers. Adjusted relative risks for death by parity were computed with the use of the generalized estimating equations framework. RESULTS: The likelihood for stillbirth (odds ratio, 3.40; 95% CI, 2.20-5.26) was significantly greater among nulliparous mothers. Neonatal (odds ratio, 1.17; 95% CI, 0.95-1.43) and infant mortality rates (odds ratio, 1.10; 95% CI, 0.92-1.32) were comparable, however. With an increase in parity, there was a consistent declining trend in the risk for stillbirth (P<.0001). CONCLUSION: Nulliparity more than triples the risk for intrauterine fetal death among triplets. This parity-related disparity underscores the need for care providers to be particularly concerned about triplet gestations among nulliparous mothers.

Adult↗
PubMed2004

The relationship between paternal age and early mortality of triplets in the United States.

We sought to determine the impact of advanced paternal age on the birth outcomes of triplets in a retrospective cohort study on 15,156 triplets born in the United States from 1995 to 1997. The study group comprised fathers aged > or = 40 years. Two control groups consisting of mature (30 to 39 years) and younger (20 to 29 years) fathers were constructed for comparison of main end points. We applied the generalized estimating equation framework to obtain relative risk estimates after capturing the effect of sibling correlations within triplet clusters. Stillbirths were 35% and 26% higher among triplets of mature and older men, respectively, whereas neonatal mortality was 28% and 23% lower among infants of mature and older fathers, respectively, using younger fathers as the referent category. Although only the relative risk for neonatal mortality comparing triplets of mature and younger fathers was statistically significant, these results constitute high indices that represent an important burden of excess early mortality at the population level. Our findings demonstrate a "shifting phenomenon" whereby a higher level of intrauterine demise was compensated by a higher rate of extrauterine survival among triplets born to older fathers.

Adult↗
PubMed2004

Stillbirths and infant deaths associated with maternal smoking among mothers aged > or =40 years: a population study.

We set out to estimate the association between smoking among pregnant women aged at least 40 years and pregnancy outcome by analyzing singleton live births in the United States between 1995 and 1997. The study group consisted of deliveries to mothers aged 40 years and older with two maternal age categories (20 to 29 and 30 to 39 years) as control. Although risks varied with maternal age, smoking was associated with a higher-than-expected risk for infant mortality in all maternal age categories. The highest rate of infant mortality associated with smoking after adjusting for confounding was among mothers aged 20 to 29 (hazard ratio [HR], 1.49; 95% confidence interval [CI], 1.28 to 1.75), while the lowest was among pregnant mothers in the 40 and above age category (HR, 1.03; 95% CI, 0.87 to 1.23). In utero fetal demise was highest among older smoking mothers (>/=40 years) and declined with decreasing age (p for trend <0.0001). In conclusion, the relationship between maternal smoking and pregnancy outcomes is modified by the age of the mother.

Adult↗
PubMed2004

Low maternal age and neonatal survival of extremely preterm twins (20-28 weeks of gestation).

OBJECTIVE: We investigated the relationship between low maternal age and neonatal survival among extremely preterm twins. METHODS: This was a retrospective cohort study on live births of extremely preterm twins delivered to teenaged mothers (aged 15-19 years) in the United States within the period 1995 through 1998. Overall neonatal and early and late neonatal mortality in this category was compared with that of a similar group of twins born to young adult mothers (aged 20-29 years). We used the generalized estimating equation framework in computing relative risks after adjusting for intracluster correlations. RESULTS: Analysis involved 2,290 extremely preterm liveborn twins of teenaged mothers and 8,709 born to young adult mothers. Overall, neonatal mortality was 29% higher among the extremely preterm twins born to teenaged mothers (adjusted odds ratio [OR] 1.29; 95% confidence interval [CI] 1.04%, 1.59%). The disparity in neonatal survival was chiefly in the early neonatal period (adjusted OR 1.34; 95% CI 1.07%, 1.67%), while late neonatal mortality was comparable (adjusted OR 0.91; 95% CI 0.58%, 1.42%). In addition, twins of teenaged mothers had significantly higher level of mortality, except for the birth weight category of 1,000-1,499 g. CONCLUSION: Low maternal age was found to be associated with elevated risk of neonatal death among extremely preterm twins. The preponderance of deaths among extremely preterm twins of teenaged mothers in the early neonatal period appeared to be responsible for the disparity in survival. This information may be useful for targeted interventions aimed at enhancing survival of extremely preterm twins born to teenagers, as well as for instituting optimal management options in the clinical setting. LEVEL OF EVIDENCE: II-2

Adolescent↗
PubMed2004

Racial disparity in stillbirth among singleton, twin, and triplet gestations in the United States.

OBJECTIVE: We investigated the relationship between maternal race and stillbirth among singletons, twins, and triplets. METHODS: We conducted a retrospective cohort study on 14,348,318 singletons, 387,419 twins, and 20,953 triplets delivered in the United States from 1995 through 1998. We compared the risk of stillbirth between pregnancies of black and those of white mothers using the generalized estimating equations framework to adjust for intracluster correlation in multiples. RESULTS: The proportion of black infants was 16%, 18%, and 8% among singletons, twins, and triplets, respectively. Crude stillbirth rate among singletons was 6.6 per 1,000 and 3.5 per 1,000 for black and white fetuses, respectively. Among twins, 796 stillbirths (11.6 per 1,000) were recorded for black mothers versus 3,209 stillbirths (10.1 per 1,000) among white mothers, whereas among triplets there were 233 stillbirths, of which 39 stillbirths were black fetuses (24.6 per 1,000) and 194 stillbirths were white fetuses (10.0 per 1,000). Black singletons, twins, and triplets weighed 278 g, 186 g, and 216 g less than white fetuses, respectively (P <.001). Risk of stillbirth was elevated in black fetuses compared with white fetuses among singletons (adjusted odds ratio [OR] 2.9, 95% confidence interval [CI] 2.8-3.0) and twins (OR 1.3. 95% CI 1.2-1.4) but comparable among triplets (OR 1.2, 95% CI 0.7-2.1). This decreasing trend was significant (P for trend <.001). CONCLUSION: The disparity of stillbirths between black and white fetuses still persists among singletons and twins. Among triplet gestations, however, the 2 racial groups have a comparable risk level. Our findings highlight the need for a rigorous research agenda to elucidate causes of stillbirth across racial/ethnic entities in the United States. LEVEL OF EVIDENCE: II-2

Adult↗
PubMed2004

Antepartum bed rest: maternal weight change and infant birth weight.

Despite lack of evidence for effectiveness, obstetricians in the United States prescribe antepartum bed rest for more than 700,000 women per year. However, in nonpregnant samples, bed rest treatment produces weight loss. This study assessed maternal weight change (gain) during antepartum hospitalization for bed rest treatment; compared appropriateness of infant birth weights for gestational age, race, and gender; and determined whether maternal weight change predicted infant birth weight. The convenience sample for this longitudinal study consisted of 141 women with high-risk pregnancies who were treated with hospital bed rest. Weekly rate of pregnancy weight change by body mass index was compared with Institute of Medicine recommendations for rate of pregnancy weight gain. Infant birth weight was compared with current US infant birth weights for matching gestational age, gender, and race. Weekly antepartum weight change was significantly lower than Institute of Medicine recommendations (P < 0.001). Infant birth weights were also significantly lower than the national mean when matched for each infant's gestational age, race, and gender (P < 0.001). Maternal weight change predicted infant birth weight (P = 0.05). Bed rest treatment is ineffective for improving pregnancy weight gain. Lower infant birth weights across all gestational ages suggest that maternal weight loss during bed rest may be associated with an increased risk of fetal growth restriction. A randomized trial comparing women with high-risk pregnancies who are ambulatory with those on bed rest is needed to determine whether bed rest treatment, underlying maternal-fetal disease, or both influence inadequate maternal weight gain and poor intrauterine growth.

Adult↗
PubMed2004

Risks in triplet pregnancy: advanced maternal age, premature rupture of membranes and risk estimates of mortality.

OBJECTIVE: To investigate the impact of older maternal age on the risk of mortality associated with premature rupture of membranes (PROM) among triplets. STUDY DESIGN: A retrospective, cohort study was performed on triplet deliveries in the United States that occurred in the period perinatal and 1995-1998. The study group comprised mothers aged > or =40 years (older mothers), who were compared to mothers aged 30-39 (mature mothers), 20-29 (younger mothers) and mothers <20 (teenagers). We computed risks of mortality associated with PROM within each maternal age category using generalized estimating equations to take into account both intracluster and intercluster sources of variation. RESULTS: The risk of stillbirth and of neonatal and perinatal mortality related to PROM was highest among teenagers. In all circumstances, the risk of both intrauterine and extrauterine death resulting from PROM diminished progressively with increasing maternal age until age 40 and beyond, at which point the risk rose once more and produced a U shape. PROM triplets of older mothers had apparently higher mortality indices than did those of younger and mature mothers, although the risk difference did not show statistical significance for any of the mortality indices. Similarly, the proportion of preventable deaths if PROM could be averted demonstrated a U-shape, consistent with that of risk estimates. CONCLUSION: Premature rupture of membranes was associated with an increase risk of perinatal and infant mortality among triplets. Although older mothers demonstrated higher risk levels for all mortality indices in comparison to younger and mature mothers, our findings did not reach statistical significance.

Adolescent↗
PubMed2004

Single motherhood and neonatal survival of twins among blacks and whites.

OBJECTIVE: We investigated whether an association existed between single motherhood and neonatal mortality among twins and whether such a linkage varied by race. STUDY DESIGN: Retrospective cohort analysis on 446,570 twin live births (between 24-44 gestational weeks inclusive) in the United States from 1995 through 1998. Neonatal survival was compared between twins of single and those of married mothers for blacks and whites separately using Cox proportional hazards regression that adjusted for the confounding effects of education, parity, adequacy of prenatal care and maternal smoking during pregnancy. The Robust Sandwich Estimator was employed to adjust for intracluster correlation. RESULTS: The rates for neonatal mortality among blacks were 34.9 per 1,000 among married and 43.4 per 1,000 among single mothers. Among whites, the rates were 20.6 per 1,000 for married and 28.9 per 1,000 for unmarried mothers. Neonatal mortality was significantly elevated among white twins of single mothers (Hazard Ratio (HR) = 1.23; 95% Confidence Interval (CI) = 1.14-1.31) and among black twins of single mothers (HR = 1.12; 95% CI = 1.01-1.25). However, when gestational age was adjusted for, the association between single motherhood and neonatal mortality disappeared. CONCLUSION: Single motherhood was a risk factor for neonatal mortality among twins, and the disparity in survival was more accentuated among whites. The association between single motherhood and neonatal mortality was explained by the preponderance of preterm births among twins of unmarried gravidas. Our findings reinforce the importance of future research to develop and test interventions that will decrease the incidence of preterm birth.

Adult↗
PubMed2003

The impact of advanced maternal age (> or = 40 years) on birth outcomes among triplets: a population study.

OBJECTIVE: The objective was to determine the impact of advanced maternal age on the birth outcomes of triplet gestations. STUDY DESIGN: A retrospective cohort study on 15,795 triplets born in the United States from 1995 to 1997. The generalized estimating equations framework was used to generate relative risks after capturing the effect of sibling correlations within triplet clusters. RESULTS: There was a 40% higher likelihood for stillbirths among older gravidas (> or = 40 years) as compared to younger mothers (20-29 years) although this was statistically non-significant. By contrast, we noted a significantly lower level of neonatal mortality (OR=0.36, 95% CI=0.19-0.67), perinatal mortality (OR=0.53; 95% CI=0.32-0.89) and infant mortality (OR=0.37; 95% CI=0.20-0.67) among older mothers. CONCLUSION: Our findings demonstrate a "shifting phenomenon" whereby a higher level of intra-uterine demise was compensated by a higher rate of extra-uterine survival among triplets born to older mothers.

Adult↗
PubMed2003

Maternal mortality in Northern Nigeria: a population-based study.

OBJECTIVES: To determine the incidence and causes of maternal mortality as well as its temporal distribution over the last decade (1990-1999). STUDY DESIGN: All maternal deaths recorded within the study period in the State of Kano, Northern Nigeria, were analyzed. Maternal mortality ratios (MMR) were computed using the Poisson assumption to derive confidence intervals around the estimates. A non-linear regression model was fitted to obtain the best temporal trajectory for MMR across the decade of study. RESULTS: A total of 4154 maternal deaths occurred among 171,621 deliveries, yielding an MMR of 2420 deaths per 100,000. Eclampsia, ruptured uterus and anemia were responsible for about 50% of maternal deaths. CONCLUSION: We found one of the highest maternal mortality ratios in the world. Maternal mortality could be reduced by half at study site with effective interventions targeted to prevent deaths from eclampsia, ruptured uterus and anemia.

Anemia↗