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Rolv Skjaerven

Publications and source records attributed to Rolv Skjaerven.

At least 19 recordsLinked to original sources
PubMed2006

Trends in fetal and infant survival following preeclampsia.

CONTEXT: Management of preeclampsia often culminates in induced delivery of a very preterm infant. While early termination protects the fetus from an intrauterine death, the newborn then faces increased risks associated with preterm delivery. This practice has increased in recent decades, but its net effect on fetal and infant survival has not been assessed. OBJECTIVE: To assess the effect on fetal and infant survival of increased rates of early delivery of preeclamptic pregnancies. DESIGN, SETTING, AND PARTICIPANTS: Population-based observational longitudinal study using registry data from 804 448 singleton first-born infants with Norwegian-born mothers and registered in the Medical Birth Registry of Norway between 1967 and 2003. MAIN OUTCOME MEASURES: Odds ratio (OR) of fetal and early childhood death in relation to preeclampsia. RESULTS: Among preeclamptic pregnancies, inductions before 37 weeks increased from 8% in 1967-1978 to nearly 20% in 1991-2003. During this period, the adjusted OR for stillbirth decreased from 4.2 (95% confidence interval [CI], 3.8-4.7) to 1.3 (95% CI, 1.1-1.7) for preeclamptic compared with nonpreeclamptic pregnancies. During the same period, the OR for neonatal death after preeclamptic pregnancy remained relatively stable (1.7 in 1967-1978 vs 2.0 in 1991-2003). Later infant and childhood mortality also showed little change. CONCLUSIONS: Fetal survival in preeclamptic pregnancies has vastly improved over the past 35 years in Norway, presumably because of more aggressive clinical management. However, the relative risk of neonatal death following a preeclamptic pregnancy has not changed over time.

Cesarean Section↗
PubMed2006

[The Mother and Child Cohort Study will give new answers].

Most severe diseases cannot be prevented. The main reason is lack of information about their causes. The Norwegian Mother and Child Cohort Study (MoBa) is a population-based cohort with 100,000 children included from fetal life. The ambitious goal is to understand the causal chains behind diseases and the comprehensive data collection will allow many diseases to be addressed. The overall goal is to come up with good preventive measures. The purpose of this article is to inform about MoBa and to stimulate enhanced use of data collected during research.

Adult↗
PubMed2006

Increased risk of placenta previa in pregnancies following IVF/ICSI; a comparison of ART and non-ART pregnancies in the same mother.

BACKGROUND: The risk of placenta previa may be increased in pregnancies conceived by assisted reproduction technology (ART). Whether the increased risk is due to factors related to the reproductive technology, or associated with maternal factors, is not known. METHODS: In a nationwide population-based study, we included 845,384 pregnancies reported to the Medical Birth Registry of Norway between 1988 and 2002 and compared the risk of placenta previa in 7568 pregnancies conceived after assisted fertilization, with the risk in naturally conceived pregnancies. To study the influence of ART more directly, we compared the risk of placenta previa between consecutive pregnancies among 1349 women who had conceived both naturally and after assisted fertilization. Odds ratios (OR), adjusted for maternal age, parity, previous Caesarean section and time interval between pregnancies were estimated using logistic regression. RESULTS: There was a six-fold higher risk of placenta previa in singleton pregnancies conceived by assisted fertilization compared with naturally conceived pregnancies [adjusted OR 5.6, 95% confidence interval (CI) 4.4-7.0]. Among mothers who had conceived both naturally and after assisted fertilization, the risk of placenta previa was nearly three-fold higher in the pregnancy following assisted fertilization (adjusted OR 2.9, 95% CI 1.4-6.1), compared with that in the naturally conceived pregnancy. CONCLUSIONS: The use of ART is associated with an increased risk of placenta previa. Our findings suggest that the increased risk may be caused by factors related to the reproductive technology.

Adult↗
PubMed2006

Associations of birth defects with adult intellectual performance, disability and mortality: population-based cohort study.

Infants born with birth defects have poorer outcomes in terms of mortality and disability, but the long-term intellectual outcome in children with birth defects is generally unknown. We assessed the long-term associations of various birth defects with mortality and disability, and evaluated whether high mortality and disability were reflected in impaired intellectual performance at age 18. In this nationwide cohort study, records of 9,186 males with and 384,384 without birth defects, registered in the Medical Birth Registry of Norway (1967-1979) were linked to the National Conscript Service (1984-1999). Mortality and disability before military draft, and intelligence test score at conscription were the main outcome measures. Males with birth defects had a relative risk for disability of 6.0 compared with males without defects. Disability was low within categories of birth defects associated with low mortality, and high within defect categories associated with high mortality. The relative risk for not being drafted was highest if maternal educational level was low. Heart defects and cleft palate were the only subgroups in which intellectual performance was lower after adjustment for maternal education, maternal age, marital status and birth order. In particular, intellectual performance was not impaired among those with multiple compared with single defects. We conclude that for the majority of birth defect categories in the present birth cohort, our hypothesis that intellectual performance would be impaired was not confirmed. Thus, there seems to be little reason to fear an adverse intellectual outcome in non-disabled surviving infants with birth defects.

Cohort Studies↗
PubMed2006

Maternal and paternal influences on length of pregnancy.

OBJECTIVE: Biological evidence suggests that both mother and fetus are involved in triggering a normal delivery. A tendency of a child to have a gestational age at birth similar to the father's could represent the effect of genes passed from the father to the fetus. Similar tendencies between mother and child could represent maternal genes passed to the fetus, as well as genes to the mother received from the grandmother that affect a woman's capacity to carry a pregnancy. METHODS: The Medical Birth Registry of Norway contains data on all births in Norway from 1967 onward. We identified 77,452 pairs of boys and girls born at term who later became parents and linked their birth data to the birth records for their first child. RESULTS: Gestational age of the child at birth increased on average 0.58 days for each additional week in the father's gestational age (95% confidence interval 0.48-0.67) and 1.22 days for each additional week in the mother's gestational age (1.21-1.32). Gestational age was, however, 0.65 days reduced for each additional kilogram in the father's birth weight, presumably due to more rapid growth of the fetus triggering delivery. CONCLUSION: Initiation of delivery has a fetal component that is heritable (passed from father and mother to child) and an additional maternal component that is also heritable. In addition, a more rapid rate of fetal growth appears to trigger delivery at earlier gestation. LEVEL OF EVIDENCE: II-2.

Adult↗
PubMed2006

Low birthweight and mortality: the tendency to repeat low birthweight and its association with early neonatal and infant morbidity and mortality.

Previous studies have demonstrated the tendency to repeat gestational age and birthweight in successive pregnancies and that this tendency is associated with infant survival. Thus, newborn outcome and survival is less favourable if the gestational age and size departs from this maternal tendency. This paper aims to study diseases or conditions that might be associated with this effect. Data were provided through a linkage between three Danish health registries: the Danish Fertility Database, the National Hospital Registry, and the Registry for Preventive Medicine. Such linkage was possible due to the use of unique ID-person numbers. The study included all 8219 second-order low-birthweight (LBW) singleton Danish births, 1980-94, of whom 7811 were liveborn. It was also required that the mother's first delivery took place during that period. The analysis considered 7803 of these births; eight were excluded due to insufficient information. Of the second-order LBW children, 26% had an elder sibling who was also LBW. Early neonatal mortality of a 'non-repeat' LBW birth was 1.3 times higher than 'repeat' LBW births [53.8 vs. 41.2 per 1000; RR 1.31; 95% CI 1.03, 1.65], as was infant mortality [78.4 vs. 60.8 per 1000; RR 1.30; 95% CI 1.06, 1.56]. Also, proportionately more LBW repeat births had Apgar scores of >or=7 after 1 and 5 min. Overall, repeat second-order LBW babies weighed 68 g more than non-repeat LBW babies (P < 0.001). At term, the weight difference was 160 g higher among repeat LBW births (P < 0.001). The mean number of hospitalisations during the first year of life was lower among repeat than non-repeat LBW babies (2.30 vs. 2.46, P < 0.001), while the mean duration of stay was 23.71 vs. 23.97 days (P > 0.05). Newborn immaturity was the most common diagnosis for hospitalisation, and infections the second most common. There were no differences between repeat and non-repeat LBW births in the proportion with each diagnosis. Apart from the differences in birthweight, we were unable to explain the improved survival for repeat compared with non-repeat LBW babies. Except for differences in Apgar scores, we observed no differences in morbidity based on registered hospitalisations during infancy.

Apgar Score↗
PubMed2005

[Why do some women only give birth to boys or to girls?].

BACKGROUND: There are more families with many children of only one sex than can be explained by unconditional probability. MATERIAL AND METHODS: Data from the Medical Birth Registry of Norway, covering more than 540,000 women with two, three and four births for the period 1967-2003, were used to study how the sex distributions of children already born affected the probability of a new birth and the sex of the next sibling. RESULTS: Women with two children of the same sex had a higher probability of having more children compared to women with two children of both sexes (RR=1.14, (1.14-1.15)). This also applied to mothers with three children (RR=1.15 (1.13-1.17)). The probability was highest for mothers with boys only. Multiple births and parity affected the probability of giving birth to a boy versus a girl, but the sex composition of already born siblings had no influence. INTERPRETATION: We have no evidence that some parents may have a probability of having a boy versus a girl that differs from the rest of the population. The fact that there are more siblings of only one sex is mainly behavioural; some mothers with only girls or only boys keep having more children in an attempt to receive a child of the opposite sex.

Birth Rate↗
PubMed2005

Recurrence of pre-eclampsia across generations: exploring fetal and maternal genetic components in a population based cohort.

OBJECTIVES: To assess the impact on risk of pre-eclampsia of genes that work through the mother, and genes of paternal origin that work through the fetus. DESIGN: Population based cohort study. SETTING: Registry data from Norway. PARTICIPANTS: Linked generational data from the medical birth registry of Norway (1967-2003): 438,597 mother-offspring units and 286,945 father-offspring units. MAIN OUTCOME MEASURES: Pre-eclampsia in the second generation. RESULTS: The daughters of women who had pre-eclampsia during pregnancy had more than twice the risk of pre-eclampsia themselves (odds ratio 2.2, 95% confidence interval 2.0 to 2.4) compared with other women. Men born after a pregnancy complicated by pre-eclampsia had a moderately increased risk of fathering a pre-eclamptic pregnancy (1.5, 1.3 to 1.7). Sisters of affected men or women, who were themselves born after pregnancies not complicated by pre-eclampsia, also had an increased risk (2.0, 1.7 to 2.3). Women and men born after pre-eclamptic pregnancies were more likely to trigger severe pre-eclampsia in their own (or their partner's) pregnancy (3.0, 2.4 to 3.7, for mothers and 1.9, 1.4 to 2.5, for fathers). CONCLUSIONS: Maternal genes and fetal genes from either the mother or father may trigger pre-eclampsia. The maternal association is stronger than the fetal association. The familial association predicts more severe pre-eclampsia.

Birth Order↗
PubMed2005

Parenthood in survivors after adulthood cancer and perinatal health in their offspring: a preliminary report.

Cancer survivors may fear infertility, obstetric problems, and genetic alterations in their offspring. After linkage of three registries the probability of post-treatment parenthood and the risk of obstetric and perinatal problems were estimated in cancer survivors compared to individuals without a cancer diagnosis. A total of 1531 of 13,817 patients had 2307 children after one parent's cancer diagnosis: 972 males had 1479 children and 559 females had 828. A total of 1217 patients (784 males and 433 females) became parents > or =9 months after the diagnosis (1899 births: 1221 to male cancer patients and 678 to female patients). The post-diagnosis parenthood probability was 8% at 5 years, and 14% at 10 years without further increase. Female cancer survivors gave birth to post-diagnosis infants with on average 130 grams lower birth weight and 6 days shorter gestations compared with infants in the non-cancer population. Infants fathered by male cancer survivors did not differ from control infants with respect to birth weight or gestational age. There was no increase in the prevalence of major congenital malformations in the offspring of cancer survivors as compared with the offspring of the non-cancer population. Multiple births and deliveries by cesarean sections were increased. Parenthood after cancer is possible in a significant number of patients, more so for males than females. The risk of major congenital malformations was not increased relative to the non-cancer population, nor was perinatal mortality increased. However, female cancer survivors delivered more preterm births and low-birth-weight infants than what was found in the non-cancer population.

Adult↗
PubMed2005

Breech delivery and intelligence: a population-based study of 8,738 breech infants.

OBJECTIVE: Long-term intellectual performance in breech-presented infants may be negatively affected by vaginal delivery. We evaluated the effect of presentation at birth and delivery mode on intellectual performance at age 18 years in a nationwide population study. METHODS: We studied 8,738 male infants in breech and 384,832 males in cephalic presentation registered in the Medical Birth Registry of Norway, 1967-1979, and linked to data registered at the National Conscript Service, 1984-1999. Test scores of intelligence testing at conscription were presented as standard nine ("stanine") scores. Mean stanine scores and odds ratios of low score were computed and adjusted for birth order, maternal age, and education. RESULTS: Mean stanine score was slightly higher among breech-presented males than among cephalic-presented males (5.26 versus 5.22, P = .05), whereas after adjustment the difference disappeared (P = .3). Breech-presented infants had lower mean scores if delivered by cesarean compared with vaginal breech delivery (P = .03), and cephalic-presented males scored lower if their mothers had a cesarean delivery instead of a vaginal delivery (P < .001). Comparing cesarean and vaginal delivery in breech births, the odds ratio of having a stanine score less than or equal to 3 was 1.12 (95% confidence interval 0.92,1.36), after adjustment for confounding factors. CONCLUSION: Presentation at birth did not affect adult intellectual performance. Cesarean delivery of breech-presented infants did not improve adult intellectual performance when compared with a vaginal delivery. The excess perinatal hazards of breech-presented infants with a vaginal delivery were not reflected in adult intellectual performance.

Adolescent↗
PubMed2005

Size at birth and gestational age as predictors of adult height and weight.

BACKGROUND: Both birth length and birth weight are associated with height in adulthood and may have independent contributions to adult body size, but the effects of gestational age on these associations have not been fully evaluated. Our objective was to examine the independent contributions of gestational age, and of length and weight at birth, on adult (age 18 years) height and weight, with a special focus on the effects of being born preterm. METHODS: In this nationwide cohort study, records of 348,706 male infants included in the Medical Birth Registry of Norway (1967-1979) were linked to the Norwegian Conscripts Service (1984-1999). Complete follow-up information, including deaths, emigration, and disability pension, was obtained for 94%. We analyzed length and weight at birth using standardized (z-scores) values and stratified by gestational age. RESULTS: The positive association between birth length and adult height was stronger than between birth weight and adult weight (R = 7-9% compared with <0.1%, respectively). The strongest associations were seen among those born at gestational age 39 to 41 weeks. The effects of birth length on adult height, and of birth weight on adult weight, were considerably less among preterm births than among term births. Length and weight at birth each contributed independently to adult stature and body weight. The increase in adult weight per relative birth weight category was greatest for infants who were both heavy and long at birth. CONCLUSIONS: Birth length is perhaps a better predictor of adult height and weight than birth weight, and should be considered as a possible risk factor for adult morbidity and mortality.

Adolescent↗
PubMed2005

Recurrence risk in hyperemesis gravidarum.

OBJECTIVES: To compare the risk of hyperemesis gravidarum in second pregnancies in women with and without hyperemesis in their first pregnancy, and to determine if this risk changes with changes in paternity or with the interval between deliveries. DESIGN: Cohort study. SETTING: Data from the population-based Medical Birth Registry of Norway, 1967-1998. Sample All women in the registry with records of their first and second singleton delivery, a total of 547,238 women. METHODS: The relative risk of hyperemesis in the second delivery was estimated as odds ratios (ORs) in logistic regression models, controlling for potential confounding factors. MAIN OUTCOME MEASURES: The main outcome measure was the risk of hyperemesis in the second pregnancy according to hyperemesis in the first pregnancy, interval between deliveries and change in paternity. RESULTS: The risk of hyperemesis was 15.2% in the second pregnancy in women with and 0.7% in women without previous hyperemesis [OR=26.4, 95% confidence interval (CI) 24.2, 28.7]. The OR did not change after adjustment for maternal age, change in paternity, period of the first delivery and time interval between deliveries. After a change in paternity, the risk of recurrent hyperemesis was 10.9% compared with 16.0% in women without a change in paternity [adjusted OR (aOR)=0.60, 95% CI 0.39, 0.92]. The risk of hyperemesis in the second pregnancy increased with increasing time interval between deliveries, but only in women with no previous hyperemesis. CONCLUSIONS: The primary finding was the high risk of recurrence observed in women with hyperemesis in the first pregnancy. The risk was reduced by a change in paternity. For women with no previous hyperemesis, a long interval between births slightly increased the risk of hyperemesis in the second pregnancy. Further studies are needed to explore the relative impact of genetic and environmental factors and their possible interactions in hyperemesis gravidarum.

Adult↗
PubMed2005

Early death, morbidity, and need of treatment among extremely premature infants.

OBJECTIVE: To determine outcomes, in terms of perinatal and early death, need for treatment, and morbidity at the time of discharge home, among extremely preterm infants. DESIGN: A prospective observational study of all infants with a gestational age (GA) of 22 to 27 completed weeks or a birth weight of 500 to 999 g who were born in Norway in 1999 and 2000. RESULTS: Of 636 births, 174 infants (27%) were stillborn or died in the delivery room, 86 (14%) died in the NICU, and 376 (59%) were discharged from the hospital. The risk of being registered as stillborn or not being resuscitated increased with decreasing GA below 25 weeks. The survival rates for all births and for infants admitted to a NICU were, respectively, 0% for <23 weeks, 16% and 39% for 23 weeks, 44% and 60% for 24 weeks, 66% and 80% for 25 weeks, 72% and 84% for 26 weeks, 82% and 93% for 27 weeks, and 69% and 90% for >27 weeks. For the survivors, days of mechanical ventilation decreased from a median of 37 days to 3 days and the proportion in need of oxygen at 36 weeks' postconceptional age decreased from 67% to 26% at 23 and 27 weeks' GA, respectively. At 40 weeks' postconceptional age, the respective figures were 11% and 6%. The proportion with retinopathy of prematurity (ROP) requiring treatment decreased from 33% for GA of 23 weeks to 0% for >25 weeks. Periventricular hemorrhage of more than grade 2 occurred for 6% of the survivors and significant periventricular leukomalacia occurred for 5%, with no significant association with GA. The proportion of survivors without severe neurosensory or pulmonary morbidity increased from 44% for 23 weeks' to 86% for 27 weeks' GA. Apart from ROP, the morbidity rate was not associated with GA. CONCLUSIONS: The survival rate was high and the morbidity rate at discharge home was low in the present study, compared with previous population-based studies. With the exception of ROP, the morbidity rates among the survivors were not higher at the lowest GAs, possibly because withholding treatment was considered more acceptable for the most immature infants. The need for intensive care increased markedly for survivors with the lowest GAs.

Female↗
PubMed2004

Paternal age and the risk of birth defects in Norway.

PURPOSE: We studied 1,869,388 births from The Medical Birth Registry of Norway to assess the effect of father's age on risks of birth defects in offspring. METHOD: Thirteen separate categories were studied including pooled categories of neural tube defects and any type of defect. We used logistic regression models to adjust for maternal age, year of birth, maternity institution, parity, and correlation between siblings. RESULTS: There was little evidence of increased risk by high paternal age for any category of defects, except for a category of "other central nervous system" where risk estimates were 2.5-fold (95% CI: 1.2-5.5) for fathers aged between 45 and 49 years compared with the reference age group (25-29 years). The risk for neural tube defects was 1.3-fold (95% CI: 1.1-1.5) when the father was aged between 20 and 24 years relative to the reference. A pattern of moderately higher risks for younger fathers was consistent for anencephaly and spina bifida. Increased risk of heart defects was also estimated among children of young fathers. CONCLUSIONS: This study does not show consistent evidence that paternal ageing is a risk for birth defects among offspring. Low paternal age, or factors associated with younger parents, may however be associated with increased risk of neural tube defects in their offspring.

Adult↗
PubMed2004

Offspring sex and pregnancy outcome by length of gestation.

BACKGROUND: It takes a higher number of male than female embryos to produce a live born infant. The unbalanced pregnancy survival by offspring sex may also be reflected in higher proportion of preterm male births, and in unbalanced sex distribution in certain pregnancy conditions, such as preeclampsia. METHODS: We used data from the Medical Birth Registry of Norway, a population-based registry that has recorded births since 1967. For this study, we used information on offspring sex and length of gestation that was available for 1691053 (92.8%) singleton births among a total of 1822982 births from 1967 to 1998. We estimated sex ratios and perinatal mortality by length of gestation, and assessed whether the ratio of offspring sex in preeclampsia varied by length of gestation. RESULTS: For preterm births, there was a strong male dominance. Within five categories of gestational age between 16 and 36 weeks, the male/female ratios were 2.48, 1.26, 1.28, 1.32, and 1.28. At weeks 37-39, the sex ratio was 1.17, but at weeks 40-42 the number of male and female births was practically identical (sex ratio 1.00). Over all, the male/female ratio was 1.06. Perinatal mortality was consistently higher in males across the whole range of gestational age; in total it was 21% (95% CI, 18-25%) higher in male offspring. In preeclampsia with preterm delivery (<37 weeks), the sex ratio was reversed: female offspring was substantially more common than males (sex ratio 0.87), but in preeclampsia with delivery at term (37-42 weeks), the proportion of males was higher (sex ratio 1.06) than for females. CONCLUSION: The sex differences by length of gestation and in preeclampsia may reflect that male embryos are subject to stronger intrauterine selection forces than females. Possibly, implantation may be the critical event, where offspring sex may be one of the factors that determine success.

Adult↗
PubMed2004

Is pre-eclampsia more than one disease?

OBJECTIVES: The clinical characteristics of pre-eclampsia (gestational hypertension and proteinuria) may represent separate pathogenetic conditions. Pre-eclampsia accompanied by restricted fetal growth may originate from abnormal implantation, and appropriate or high birthweights may indicate a mixture of conditions, ranging from mild pre-eclampsia with modest placental involvement to hypertensive conditions without placental disease. DESIGN: Prospective, observational study. SETTING: General population. POPULATION: We used data from the Medical Birth Registry of Norway, a population-based registry that has recorded births since 1967. For this study, we used information on length of gestation and presence of pre-eclampsia among 1,679,205 singletons born between 1967 and 1998. Pre-eclampsia was diagnosed in 44,220 (2.6%) pregnancies. METHODS: We studied the risk of pre-eclampsia in relation to standardised measures (z scores) of birthweight, adjusted for length of gestation, and stratified by term and preterm delivery. We also explored whether gestational diabetes was more prevalent in conjunction with preterm than term pre-eclampsia. MAIN OUTCOME MEASURES: Pre-eclampsia diagnosed at term or preterm. RESULTS: For pre-eclampsia diagnosed around term, there was a U-shaped association with birthweight. Compared with appropriate birthweights for gestation, the risk of term pre-eclampsia was more than fourfold higher (relative risk [RR] 4.5, 95% confidence interval [CI], 4.3 to 4.7) if the baby's birthweight was lower than two standard deviations under the mean. For birthweights three standard deviations or higher than the mean, pre-eclampsia was more than twice as likely (RR 2.6, 95% CI 2.2-2.9). In contrast, the risk of preterm pre-eclampsia displayed an L-shaped association with birthweight. Low birthweight (less than -2 standard deviations) was associated with greatly increased risk (RR 9.9, 95% CI 9.1-10.9), but for high birthweights (>or=3 standard deviations), there was no association with the risk of preterm pre-eclampsia (RR 1.2, 95% CI 0.7-2.1). The prevalence of gestational diabetes was three times (prevalence ratio 3.3, 95% CI 2.6-3.6) higher in preterm than term pre-eclampsia. CONCLUSION: Whereas pre-eclampsia with preterm delivery associated with low birthweight may be caused by underlying placental abnormality, pre-eclampsia delivered at term may represent a mixture of conditions, ranging from mild pre-eclampsia with moderate placental affection to hypertensive conditions in pregnancy without placental dysfunction.

Adult↗
PubMed2003

[Change of partner between births and adverse pregnancy outcomes].

BACKGROUND: Childbearing with different fathers has increased in western societies because of the higher frequency of divorce and remarriage. Pregnancy outcomes may differ between mothers who have changed partner between first and second birth and mothers who have the same father for both births. Women who change partner may have individual characteristics that increase risk of adverse outcomes, but change of partner could also be associated with unfavourable changes in behaviour. MATERIAL AND METHODS: The Medical Birth Registry of Norway was established in 1967 and includes information on approximately 1.8 million births until 1998. Both parents are recorded. We have compared pregnancy outcomes for 30 176 mothers who changed partner between first and second birth and 461 154 mothers who had the same partner for both births. RESULTS: In relation to the first birth, the risk of adverse pregnancy outcomes was not clearly different between mothers who later had a second birth with another partner and mothers who had the same partner for both births. Offsprings of mothers who changed partner between first and second birth were at higher risk of infant mortality (relative risk 1.5, 95 % confidence interval, 1.3-1.7), preterm birth (< 37 weeks; relative risk 1.3, 95 % confidence interval, 1.2-1.4), and low birth weight (< 2500 gram; relative risk 1.5, 95 % confidence interval, 1.4-1.6), after adjustment for maternal age and level of education, interval between births, and time period. INTERPRETATION: Mothers who change partner between first and second birth are at increased risk of having a preterm, low birth weight baby with increased risk of infant death for the second child compared to mothers who have the same partner for both births.

Birth Order↗