From infancy to pregnancy: birth weight, body mass index, and the risk of gestational diabetes

Obesity is a risk factor for gestational diabetes, whereas the role of the mother’s birth weight is more uncertain. We aimed to investigate the combined effect of mothers’ birth-weight-for-gestational-age and early pregnancy Body Mass Index (BMI) in relation to risk of gestational diabetes. Between 1973 and 2006, we identified a cohort of 323,083 women included in the Swedish Medical Birth Register both as infants and as mothers. Main exposures were mothers’ birth-weight-for-gestational-age (categorized into five groups according to deviation from national mean birth weight) and early pregnancy BMI (classified according to WHO). Rates of gestational diabetes increased with adult BMI, independently of birth-weight-for-gestational-age. However, compared to women with appropriate birth-weight-for-gestational-age [appropriate-for-gestational age (AGA); ?1 to +1 SD] and BMI (<25.0), women with obesity class II-III (BMI?≥?35.0) had an adjusted odds ratio (OR) of 28.7 (95?% confidence interval, CI 17.0–48.6) for gestational diabetes if they were born small-for-gestational-age [small for gestational age (SGA); <?2SD], OR?=?20.3 (95?% CI 11.8–34.7) if born large-for-gestational-age [large-for-gestational-age (LGA); >2SD], and OR?=?10.4 (95?% CI 8.4–13.0) if born AGA. Risk of gestational diabetes is not only increased among obese women, but also among women born SGA and LGA. Severely obese women born with a low or a high birth-weight-for-gestational-age seem more vulnerable to the development of gestational diabetes compared to normal weight women. Normal pre-pregnancy BMI diminishes the increased risk birth size may confer in terms of gestational diabetes. Therefore, the importance of keeping a healthy weight cannot be overemphasized.     

Assessment of the Institute of Medicine Recommendations for Weight Gain During Pregnancy: Florida, 2004–2007

We investigated the association between 2009 IOM recommendations and adverse infant outcomes by maternal prepregnancy body mass index (BMI). Birth outcomes for 570,672 women aged 18–40 years with a singleton full-term live-birth were assessed using 2004–2007 Florida live-birth certificates. Outcomes included large-for-gestational-age (LGA) and small-for-gestational-age (SGA). Associations between gestational weight change and outcomes were assessed for 10 BMI groups by calculating proportions, and logistic regression modeling was used to produce adjusted odds ratios (aORs) to account for the effect of confounders. We created comparison categories below and above recommendations using 2009 IOM recommendations as a reference. Of importance, 41.6% of women began pregnancy as overweight and obese and 51.2% gained weight excessively during pregnancy on the basis of 2009 IOM recommendations. Proportions of LGA were higher among obese women and increased with higher weight gain. Compared with recommended weight gain, aORs for LGA were lower with less than recommended gain (aOR range: 0.27–0.77) and higher with more than recommended gain (aOR range: 1.27–5.99). However, SGA was less prevalent among obese women, and the proportion of SGA by BMI was similar with higher weight gain. Gain less than recommended was associated with increased odds of SGA (aOR range: 1.11–2.97), and gain greater than recommended was associated with decreased odds of SGA (aOR range: 0.38–0.83). Gestational weight gain influenced the risk for LGA and SGA in opposite directions. Minimal weight gain or weight loss lowered risk for LGA among obese women. Compared with 1990 IOM recommendations, 2009 recommendations include weight gain ranges that are associated with lower risk of LGA and higher risk of SGA. Awareness of these tradeoffs may assist with clinical implementation of the 2009 IOM gestational weight gain recommendations. However, our results did not consider other maternal and infant outcomes related to gestational weight gain; therefore, the findings should be interpreted with caution.     

The Impact of Gestational Weight Gain on the Risks of Adverse Maternal and Infant Outcomes among Normal BMI Women with High Triglyceride Levels during Early Pregnancy

A high maternal triglyceride (mTG) level during early pregnancy is linked to adverse pregnancy outcomes, but the use of specific interventions has been met with limited success. A retrospective cohort study was designed to investigate the impact of gestational weight gain (GWG) on the relationship between high levels of mTG and adverse pregnancy outcomes in normal early pregnancy body mass index (BMI) women. The patients included 39,665 women with normal BMI who had a singleton pregnancy and underwent serum lipids screening during early pregnancy. The main outcomes were adverse pregnancy outcomes, including gestational hypertension, preeclampsia, gestational diabetes, cesarean delivery, preterm birth, and large or small size for gestational age (LGA or SGA) at birth. As a result, the high mTG (≥2.05mM) group had increased risks for gestational hypertension ((Adjusted odds ratio (AOR), 1.80; 95% CI, 1.46 to 2.24)), preeclampsia (1.70; 1.38 to 2.11), gestational diabetes (2.50; 2.26 to 2.76), cesarean delivery (1.22; 1.13 to 1.32), preterm birth (1.42, 1.21 to 1.66), and LGA (1.49, 1.33 to 1.68) compared to the low mTG group, after adjustment for potential confounding factors. Additionally, the risks of any adverse outcome were higher in each GWG subgroup among women with high mTG than those in the low mTG group. High mTG augmented risks of gestational hypertension, preeclampsia, preterm birth, and LGA among women with 50th or greater percentile of GWG. Interestingly, among women who gained less than the 50th percentile of GWG subgroups, there was no relationship between high mTG level and risks for those pregnancy outcomes when compared to low mTG women. Therefore, weight control and staying below 50th centile of the suggested GWG according to gestational age can diminish the increased risks of adverse pregnancy outcomes caused by high mTG during early pregnancy.     

Pre-pregnancy Body Mass Index, Gestational Weight Gain, and Other Maternal Characteristics in Relation to Infant Birth Weight

Objectives Infant birth weight is influenced by modifiable maternal pre-pregnancy behaviors and characteristics. We evaluated the relationship among pre-pregnancy body mass index (BMI), gestational weight gain, and infant birth weight, in a prospective cohort study. Methods Women were enrolled at ≤20 weeks gestation, completed in-person interviews and had their medical records reviewed after delivery. Infant birth weight was first analyzed as a continuous variable, and then grouped into Low birth weight (LBW) (<2,500 g), normal birth weight (2,500–3,999 g), and macrosomia (≥4,000 g) in categorical analysis. Pre-pregnancy BMI and gestational weight gain were categorized based on Institute of Medicine BMI groups and gestational weight gain guidelines. Associations among infant birth weight and pre-pregnancy BMI, gestational weight gain, and other factors were evaluated using multivariate regression. Risk ratios were estimated using generalized linear modeling procedures. Results Pre-pregnancy BMI was independently and positively associated with infant birth weight (β = 44.7, P = 0.001) after adjusting for confounders, in a quadratic model. Gestational weight gain was positively associated with infant birth weight (β = 19.5, P < 0.001). Lower infant birth weight was associated with preterm birth (β = −965.4, P < 0.001), nulliparity (β = −48.6, P = 0.015), and female babies (β = −168.7, P < 0.001). Less than median gestational weight gain was associated with twice the risk of LBW (RR = 2.04, 95% CI 1.34–3.11). Risk of macrosomia increased with increasing pre-pregnancy BMI and gestational weight gain (P for linear trend <0.001). Conclusions These findings support the need to balance pre-pregnancy weight and gestational weight gain against the risk of LBW and macrosomia among lean and obese women, respectively.     

孕前体重指数和孕期体重增加对大于胎龄儿和巨大儿发生风险的影响

目的:探讨孕前体重指数(BMI)和孕期体重增加对大于胎龄儿(LGA)和巨大儿发生风险的影响。方法:回顾性分析6562例次足月单胎分娩的孕妇孕前和孕期产检资料,按孕前BMI值分为偏瘦组(BMI18.5)、正常体重组(18.5≤BMI24.0)、超重组(24.0≤BMI27.0)和肥胖组(BMI≥27.0),分别计算4组孕妇在孕期体重不同程度增加的情况下发生LGA和巨大儿的相对风险值(OR)。结果:孕前BMI越高,孕期体重增加越多,分娩LGA和巨大儿的风险和比例越高。孕前偏瘦组的妇女,孕期体重增加超过18.0kg时,发生LGA的风险高于其他孕前BMI组;孕期体重增加超过25.0kg时,则发生LGA和巨大儿的风险均明显高于其他孕前BMI组。结论:孕前BMI和孕期体重增加过多均对LGA和巨大儿的发生有很大影响,应在保证营养的条件下,尽可能控制孕期体重的增加。     

Maternal weight change before pregnancy in relation to birthweight and risks of adverse pregnancy outcomes

Maternal weight change before pregnancy can be considered as an indicator of maternal energy balance and nutritional status before conception, and may be involved in early life programming. We aimed to investigate the association of maternal Weight Change Before Pregnancy (WCBP) with fetal growth and adverse pregnancy outcomes. Data are from the French EDEN mother–child cohort where 1,756 mother–child pairs had information on mother’s weight at 20 years, weight just before pregnancy, fetal anthropometry at second and third trimesters, infant’s birthweight and pregnancy complications. The average annual WCBP between 20 years and start of pregnancy (in kg/year) was categorized as: “Weight Loss” (n = 320), “Moderate weight gain” (n = 721) and “High weight gain” (n = 715). The associations of WCBP with fetal and newborn characteristics and with adverse pregnancy outcomes were analyzed, adjusting for maternal and pregnancy characteristics, including the mother’s prepregnancy BMI. Interactions between WCBP and prepregnancy BMI were tested. Birthweight and estimated fetal weight in the third trimester increased significantly with increasing WCBP in mothers with BMI <25 kg/m². In these mothers, weight loss before pregnancy was associated with a higher risk of newborns small for gestational age (SGA). Whatever the prepregnancy BMI, WCBP was positively associated with a maternal risk of gestational diabetes and hypertension. The ponderal history of mothers before pregnancy can impact on fetal growth and on pregnancy outcomes such as gestational diabetes or hypertension. Our analysis is the first to report that in non-overweight women, those who lost weight before pregnancy are at higher risk of having SGA newborns.     

Gestational Diabetes and Subsequent Growth Patterns of Offspring: The National Collaborative Perinatal Project

Our objective was to test the hypothesis that intrauterine exposure to gestational diabetes [GDM] predicts childhood growth independent of the effect on infant birthweight. We conducted a prospective analysis of 28,358 mother-infant pairs who enrolled in the National Collaborative Perinatal Project between 1959 and 1965. The offspring were followed until age 7. Four hundred and eighty-four mothers (1.7%) had GDM. The mean birthweight was 3.2 kg (range 1.1–5.6 kg). Maternal characteristics (age, education, race, family income, pre-pregnancy body mass index and pregnancy weight gain) and measures of childhood growth (birthweight, weight at ages 4, and 7) differed significantly by GDM status (all P < 0.05). As expected, compared to their non-diabetic counterparts, mothers with GDM gave birth to offspring that had higher weights at birth. The offspring of mothers with GDM were larger at age 7 as indicated by greater weight, BMI and BMI z-score compared to the offspring of mothers without GDM at that age (all P < 0.05). These differences at age 7 persisted even after adjustment for infant birthweight. Furthermore, the offspring of mothers with GDM had a 61% higher odds of being overweight at age 7 compared to the offspring of mothers without GDM after adjustment for maternal BMI, pregnancy weight gain, family income, race and birthweight [OR = 1.61 (95%CI:1.07, 1.28)]. Our results indicate that maternal GDM status is associated with offspring overweight status during childhood. This relationship is only partially mediated by effects on birthweight.     

Maternal Weight Gain During Pregnancy and Child Weight at Age 3 Years

Objectives To determine the importance of pregnancy weight gain as a predictor of overweight (Body Mass Index [BMI] >85th percentile) in offspring at age 3 years and if its influence varies by maternal BMI. Methods Chi-square and logistic regression analyses were conducted on a sample of 208 mother-child pairs from an earlier observational cohort study on postpartum weight retention. Results In the final reduced regression model, maternal early pregnancy BMI was positively and significantly associated with overweight in offspring, as were birth weight above the sample median of 3,600 g and maternal smoking during pregnancy (P ≤ 0.01). In addition, a significant interaction was found between maternal BMI and gestational weight gain (P = 0.03). The risk of offspring overweight that is associated with 5 excess pounds of net pregnancy weight gain increases with maternal BMI. Conclusions Excess pregnancy weight gain is associated with increased risk of child overweight at age 3 years and its impact is greater among high and obese BMI women than it is in normal BMI women. Reducing maternal BMI in the preconception period in overweight women and preventing excessive weight gain in pregnancy for all women appear to be appropriate strategies to address the childhood obesity epidemic.     

Predictors of Obesity in Childhood,Adolescence, and Adulthood in a Birth Cohort

To determine how characteristics of pregnancy, birth, and early infancy are related to offspring obesity at three critical developmental periods. Mothers were followed through pregnancy and 10–15 years after. Offspring data were obtained through medical record review. Maternal and offspring characteristics were examined to predict obesity in childhood (ages 4–5 years), adolescence (ages 9–14 years), and early adulthood (ages 19–20 years). The original cohort included 802 children born to 795 women. Children who were twins, who had died, or whose mothers had died were excluded (n = 25). Medical records of 68.5% of the remaining 777 children documented a height and weight at childhood, adolescence, or early adulthood. Relative risks (RRs) to predict obesity at early adulthood were 12.3 for childhood and 45.1 at adolescence. RRs were also significant to predict obesity at early adulthood between the mother’s obesity at prepregnancy (RR = 6.4), 4–5 years postpregnancy (RR = 6.3), and 10–15 years postpregnancy (RR = 6.2). Excluding these variables from the multivariate models and adjusting by gender, birth insurance, and mother’s marital status at delivery, the best model to predict obesity at childhood included birth weight, weight gain in infancy, and delivery type. At adolescence, it included maternal pregnancy smoking status, gestational weight gain, and weight gain in infancy, and in early adulthood, included maternal pregnancy smoking status, gestational weight gain, and birth weight. Maternal pregnancy smoking status, gestational weight gain, and weight gain in infancy have long-term effects on offspring. Maternal obesity is the strongest predictor of obesity at all times studied.     

Second Trimester Insulin Resistance,Early Pregnancy Body Mass Index and Gestational Weight Gain

Objectives Because prior work suggests an association between high insulin concentrations in early pregnancy and excess gestational weight gain, we examined such associations in a prospective cohort. Methods Multivariate regression analysis of early pregnancy insulin homeostasis and gestational weight gain among 434 women enrolled in the MGH Obstetrical Maternal Study. Results We found that the association between insulin quartile and gestational weight gain varied depending on maternal body mass index (BMI) in early pregnancy (P for interaction <0.0001). Among women with a BMI of 20, high fasting insulin was associated with greater gestational weight gain (multivariate-adjusted predicted mean 39.6, 95% CI 30.9–40.3 lbs for Quartile 4 (Q4) vs. 31.3, 95% CI 28.6–34.1 lbs for Q1) and higher risk of excessive weight gain. By contrast, among women with a BMI of 35, higher fasting insulin was associated with lower total gain (multivariate-adjusted predicted mean 25.7, 95% CI 22.6–28.7 lbs for Q4 vs. 33.2, 95% CI 10.5–55.9 lbs for Q1) and lower risk of excessive gain. Conclusion In our cohort, early pregnancy BMI modified the association between insulin homeostasis and gestational weight gain. These associations suggest that the physiologic consequences of hyperinsulinemia differ between normal weight and obese women.     

First and second pregnancy outcomes in women with class III obesity: An observational cohort study

IntroductionClass III obesity (BMI ≥ 40 kg/m²) during pregnancy predisposes mother and offspring to a range of adverse pregnancy complications and outcomes. Risk profiles vary between pregnancies and are affected by interpregnancy weight gain. We evaluated the risk of adverse outcomes in women with BMI ≥ 40 kg/m² in first and second pregnancies, and the impact of interpregnancy weight change on this risk.Materials and methodsData were extracted for all women with BMI ≥ 40 kg/m² at first antenatal visit, who completed antenatal and delivery care for first and second pregnancies in NHS Lothian between 1/1/2009–31/12/2018. Multiple pregnancies and recipients of bariatric surgery were excluded.Results442 pregnancies among 221 women were included. In first pregnancy, median (interquartile range) weight was 117 kg (108.5–126.7), age 28 years (24–31) and BMI 42 kg/m² (41.0?44.5), 14.4% had gestational diabetes (GDM), 11.3% had pregnancy-induced hypertension and 44.6% had a post-partum haemorrhage (PPH). 20.8% of babies were large for gestational age (LGA, ≥97% centile at birth). In second pregnancy, women were heavier with a median weight of 119.9 kg (109.0?130.0, p = 0.00) with 19.9% gaining over 10 kg. Women were more likely to develop GDM (21.6%, p = 0.02). Babies were heavier with 40% of babies LGA (p < 0.0001). Interpregnancy weight change had no significant impact on GDM, pregnancy induced hypertension, PPH, perinatal mortality or LGA.ConclusionsIn a population of women with BMI ≥ 40 kg/m², pregnancy complications are common and risk is higher in second pregnancy. The interpregnancy period is a critical time to engage women in health improvement and weight loss strategies to maximise outcomes for mother and offspring.     

The association between gestational weight gain and risk of stillbirth: a population-based cohort study

PurposeTo estimate the risk of stillbirth associated with excessive and inadequate weight gain during pregnancy.MethodsRetrospective cohort study using the Texas vital records database between 2006 and 2011, with 2,230,310 births (5502 stillbirths) was included for analysis. Pregnancies were categorized as adequate weight gain, excessive weight gain, inadequate weight gain, or weight loss based on the Institute of Medicine 2009 recommendations. Hazard ratios (HRs) for stillbirth were estimated for each gestational weight-gain stratum using adequate weight gain as the comparison group. The analysis was performed separately for each body mass index (BMI) class.ResultsBoth inadequate weight gain and weight loss were associated with an increased risk of stillbirth for all BMI classes except the morbidly obese group. Highest risk was seen in weight-loss groups after 36 completed weeks (normal weight: HR = 18.85 [8.25–43.09]; overweight: HR = 5.87 [2.99–11.55]; obese: HR = 3.44 [2.34–5.05]). Weight loss was associated with reduced stillbirth risk in morbidly obese women between 24 and 28 weeks (HR = 0.56 [0.34–0.95]). Excess weight gain was associated with an increased risk of stillbirth among obese and morbidly obese women, with highest risk after 36 completed weeks (obese: HR = 2.00 [1.55–2.58]; morbidly obese: HR = 3.16 [2.17–4.62]). In contrast, excess weight gain was associated with reduced risk of stillbirth in normal-weight women between 24 and 28 weeks (HR = 0.57 [0.44–0.70]) and in overweight women between 29 and 33 weeks (HR = 0.62 [0.45–0.85]). Analysis for the underweight group was limited by sample size. Both excessive weight gain and inadequate weight gain were not associated with stillbirth in this group.ConclusionsStillbirth risk increased with inadequate weight gain and weight loss in all BMI classes except the morbidly obese group, where weight demonstrated a protective effect. Conversely, excessive weight gain was associated with higher risk of stillbirth among obese and morbidly obese women but was protective against stillbirth in lower weight women.     

Prepregnancy body mass index and gestational weight gain as risk factors for preeclampsia and transient hypertension

PURPOSE: Recent studies suggest prepregnancy obesity is a risk factor for preeclampsia, although only a handful of studies have examined the effect of gestational weight gain. The authors analyzed the effect of prepregnancy body mass index (BMI) and weight gain during pregnancy on risk of preeclampsia and transient hypertension.METHODS: Subjects were participants in a prospective cohort study of women who received prenatal care from thirteen obstetric practices in southern Connecticut (4/88-12/91). The women were interviewed in-person before 16 weeks gestation and in the immediate postpartum period. All subjects' hospital delivery charts were abstracted. BMI was categorized as: <19.8 (underweight), 19.8-26 (normal: referent), 26-29 (overweight), >29 (obese). A gestational weight gain index, created using multiple linear regression, compared observed weight gain to the weight gain expected after adjustment for significant covariables (e.g. gestational aged at delivery). Logistic regression was used to estimate risk of preeclampsia (N = 44) and transient hypertension (N = 172) associated with prepregnancy BMI and gestational weight gain.RESULTS: Obese women had a mild increased risk of preeclampsia (OR = 1.81; 0.73-4.52); women in the other BMI categories had risks similar to that of normal BMI subjects. In contrast, risk of transient hypertension was substantially decreased among underweight women (OR = 0.35; 0.14-0.87) and substantially increased among obese women (OR = 3.43; 2.27-5.21). Higher than expected gestational weight gain did not increase the risk of preeclampsia. In contrast, risk of transient hypertension was increased over twofold among women in the highest quartile of the weight gain index (OR = 2.55; 1.66-3.92).CONCLUSIONS: Obesity appears to be a strong risk factor for transient hypertension and a milder risk factor for preeclampsia. High gestational weight gain was associated with increased risk of transient hypertension but not preeclampsia.     

妊娠期间增重及妊娠晚期体质量指数对产后泌乳的影响

目的 探讨妊娠期间增重状况及妊娠晚期体质量指数对产后泌乳的影响.方法 选取2012年7月至2015年9月在温州市中心医院妇产科分娩的产妇623例,依据泌乳水平分为A组(泌乳量>45mL,泌乳始动时间≤48h)和B组(泌乳量≤45mL,泌乳始动时间>48h),比较两组产妇分娩后24h泌乳素、泌乳量及泌乳始动率,对两组产妇的临床资料进行单因素和多因素Logistic回归分析.结果 A组产妇的泌乳素、泌乳量均显著高于B组(t值分别为2.357、2.093,均P<0.05),且泌乳始动率显著高于B组(χ2=6.108,P<0.05).两组产妇的年龄、分娩孕周、分娩方式、妊娠晚期体质量指数、妊娠期增重、妊娠期高血压疾病、妊娠期糖尿病比较均有显著性差异(χ2=3.893~8.324,均P<0.05),而产次、新生儿体重比较无显著性差异(χ2值分别为0.687、2.451,均P>0.05).对单因素分析中有统计学意义的因素进行多因素Logistic回归分析,结果显示产妇年龄大、妊娠晚期体质量指数高、妊娠期增重过多是影响产妇泌乳水平的独立危险因素(OR值分别为2.942、2.012、3.522,均P<0.05).结论 妊娠晚期体质量指数过高、增重过多是影响产妇泌乳水平的独立危险因素,产妇应在妊娠期加强锻炼,避免肥胖.     

Singleton Preterm Birth: Risk Factors and Association with Assisted Reproductive Technology

The objectives of this study were to determine risk factors for early (less than 34 weeks gestation) and late (34–36 weeks gestation) preterm singleton birth, by assisted reproductive technology (ART) status. We linked data from Massachusetts birth records and ART records representing singleton live births from 1997 through 2004. Using multinomial regression models, we assessed risk factors for early and late preterm birth by ART status. From 1997 to 2004 in Massachusetts, among non-ART births, risk factors for early and late preterm birth were similar and included women <15 and ≥35 years of age, those of non-white race or Hispanic ethnicity, those with ≤12 years of education, those with chronic diabetes, those with gestational diabetes, those with gestational hypertension, those who smoked during pregnancy, those who used fertility medications, and those who had not had a previous live birth. Among ART births, risk factors for early and late preterm birth differed and odds of early preterm birth were increased among women with ≤12 years of education while odds of late preterm birth were increased among women with gestational diabetes. Odds of both early and late preterm birth were increased among women of non-white race or Hispanic ethnicity and among women with gestational hypertension. Among non-ART births, increased risk for preterm birth was more strongly related to socioeconomic factors than among ART births. Medical conditions were associated with an increased risk for preterm birth regardless of women’s ART status. Efforts to prevent preterm births should focus on reducing modifiable risk factors.     

The association of daily physical activity and birth outcome: a population-based cohort study

The potential relationship between daily physical activity and pregnancy outcome remains unclear because of the wide variation in study designs and physical activity assessment measures. We sought to prospectively quantify the potential effects of the various domains of physical activity on selected birth outcomes in a large unselected population. The sample consisted of 11,759 singleton pregnancies from the Avon longitudinal study of parents and children, United Kingdom. Information on daily physical activity was collected by postal questionnaire for self-report measures. Main outcome measures were birth weight, gestational age at delivery, preterm birth and survival. After controlling for confounders, a sedentary lifestyle and paid work during the second trimester of pregnancy were found to be associated with a lower birth weight, while ‘bending and stooping’ and ‘working night shifts’ were associated with a higher birth weight. There was no association between physical exertion and duration of gestation or survival. Repetitive boring tasks during the first trimester was weakly associated with an increased risk of preterm birth (<37 weeks) (adjusted odds ratio [OR] = 1.25, 95% CI 1.04–1.50). ‘Bending and stooping’ during the third trimester was associated with a reduced risk of preterm birth (adjusted OR = 0.73, 95% CI 0.63–0.84). Demanding physical activities do not have a harmful effect on the selected birth outcomes while a sedentary lifestyle is associated with a lower birth weight. In the absence of either medical or obstetric complications, pregnant women may safely continue their normal daily physical activities should they wish to do so.     

The effects of maternal body mass index on pregnancy outcome

The increasing prevalence of obesity is presenting a critical challenge to healthcare services. We examined the effect of Body Mass Index in early pregnancy on adverse pregnancy outcome. We performed a population register-based cohort study using data from the North Western Perinatal survey (N = 99,403 babies born during 2004–2006), based at The University of Manchester, UK. The main outcome measures were Caesarean section delivery, preterm birth, neonatal death, stillbirth, Macrosomia, small for gestational age and large for gestational age. The risk of preterm birth was reduced by almost 10% in overweight (RR = 0.89, [95% CI: 0.83, 0.95]) and obese women (RR = 0.90, [95% CI: 0.84, 0.97]) and was increased in underweight women (RR = 1.33, [95% CI: 1.16, 1.53]). Overweight (RR = 1.17, [95% CI: 1.09, 1.25]), obese (RR = 1.35, [95% CI: 1.25, 1.45]) and morbidly obese (RR = 1.24, [95% CI: 1.02, 1.52]) women had an elevated risk of post-term birth compared to normal women. The risk of fetal macrosomia and operative delivery increased with BMI such that morbidly obese women were at greatest risk of both (RR of macrosomia = 4.78 [95% CI: 3.86, 5.92] and RR of Caesarean section = 1.66 [95% CI: 1.61, 1.71] and a RR of emergency Caesarean section = 1.59 [95% CI: 1.45, 1.75]). Excessive leanness and obesity are associated with different adverse pregnancy outcomes with major maternal and fetal complications. Overweight and obese women have a higher risk of macrosomia and Caesarean delivery and lower risk of preterm delivery. The mechanism underlying this association is unclear and is worthy of further investigation.     

The impact of past pregnancy experience on subsequent perinatal outcomes

In perinatal epidemiology, the basic unit of analysis has traditionally been the individual pregnancy. In this study, we sought to explore the idea of a 'reproductive life'-based approach to modelling the effects of reproductive exposures and outcomes, where the basic unit of analysis is a woman's entire reproductive experience. Our objective was to explore whether a first pregnancy risk factor, excess gestational weight gain, has a direct effect on the birthweight outcomes of a subsequent pregnancy, independent of the weight gain and other risk factors of the second pregnancy. A study population was created by linking the obstetric records of 1220 women who delivered their first and second offspring at a McGill University teaching hospital in Montreal, Canada. Multivariable linear and logistic regression analyses were used to model the effects of gestational weight gain above recommendation on the birthweight Z-score and risk of large-for-gestational age (LGA) subsequent offspring. After adjusting for the risk factors of the second pregnancy, an independent effect from the first pregnancy was seen on the birthweight Z-score, (effect size OR 0.17 [95% CI 0.05, 0.28] but not risk of LGA of the second pregnancy 1.30 [95% CI 0.89, 1.89]). We concluded that a pregnancy-centred approach to research that conceptualizes pregnancies as self-contained and interchangeable events may not always be appropriate, and propose that analytical methods for some perinatal research questions may need to consider a given pregnancy in the context of a woman's past reproductive experiences.     

Impact of the Red River Catastrophic Flood on Women Giving Birth in North Dakota, 1994–2000

To document changes in birth rates, birth outcomes, and pregnancy risk factors among women giving birth after the 1997 Red River flood in North Dakota. We analyzed detailed county-level birth files pre-disaster (1994–1996) and post-disaster (1997–2000) in North Dakota. Crude birth rates and adjusted fertility rates were calculated. The demographic and pregnancy risk factors were described among women delivering singleton births. Logistic regression was conducted to examine associations between the disaster and low birth weight (<2,500 g), preterm birth (<37 weeks), and small for gestational age infants adjusting for confounders. The crude birth rate and direct-adjusted fertility rate decreased significantly after the disaster in North Dakota. The proportion of women giving birth who were older, non-white, unmarried, and had a higher education increased. Compared to pre-disaster, there were significant increases in the following maternal measures after the disaster: any medical risks (5.1–7.1%), anemia (0.7–1.1%), acute or chronic lung disease (0.4–0.5%), eclampsia (0.3–2.1%), and uterine bleeding (0.3–0.4%). In addition, there was a significant increase in births that were low birth weight (OR 1.11, 95% CI 1.03–1.21) and preterm (OR 1.09, 95% CI 1.03–1.16) after adjusting for maternal characteristics and smoking. Following the flood, there was an increase in medical risks, low birth weight, and preterm delivery among women giving birth in North Dakota. Further research that examines birth outcomes of women following a catastrophic disaster is warranted.     

Alcohol Consumption During Pregnancy and Risk of Placental Abruption and Placenta Previa

The purpose of this study was to examine the association between prenatal alcohol consumption and the occurrence of placental abruption and placenta previa in a population-based sample. We used linked birth data files to conduct a retrospective cohort study of singleton deliveries in the state of Missouri during the period 1989 through 2005 (n = 1,221,310). The main outcomes of interest were placenta previa, placental abruption and a composite outcome defined as the occurrence of either or both lesions. Multivariate logistic regression was used to generate adjusted odd ratios, with non-drinking mothers as the referent category. Women who consumed alcohol during pregnancy had a 33% greater likelihood for placental abruption during pregnancy (adjusted odds ratio (OR), 95% confidence interval (CI) = 1.33 [1.16–1.54]). No association was observed between prenatal alcohol use and the risk of placenta previa. Alcohol consumption in pregnancy was positively related to the occurrence of either or both placental conditions (adjusted OR [95% CI] = 1.29 [1.14–1.45]). Mothers who consumed alcohol during pregnancy were at elevated risk of experiencing placental abruption, but not placenta previa. Our findings underscore the need for screening and behavioral counseling interventions to combat alcohol use by pregnant women and women of childbearing age.