Moderate alcohol drinking and risk of preterm birth

OBJECTIVE: We have analysed the association between alcohol drinking before and during the three trimesters of pregnancy and risk of preterm birth of babies with normal weight for gestational age or with low weight for gestational age (SGA). DESIGN: Case-control study. SETTING: General and university hospitals in Italy. SUBJECTS: Cases were 502 women who delivered preterm births <37 weeks gestation. The controls included 1966 women who gave birth at term (>/=37 weeks of gestation) to healthy infants of normal weight (ie between 10th and 90th centile according to the Italian standard) on randomly selected days at the hospitals where cases had been identified. INTERVENTIONS: Interview. RESULTS: No increased risk of preterm birth was observed in women drinking one or two drinks/die in pregnancy, but three or more drinks/die increased the risk (multivariate odds ratios (OR) 2.0 for >/=3 drinks during the first trimester, 1.8 during the second and 1.9 during the third). When the analysis was conducted separately for preterm births with normal weight or SGA, the increased risk was observed in preterm SGA only (multivariate OR for >/=3 drinks/die during the first trimester=3.6, 95% confidence interval (CI) 1.3-11.1); the estimated multivariate OR for >/=3 drinks/die during the first trimester of preterm babies with normal weight for gestational age was only slightly above unity and not statistically significant (multivariate OR 1.4, 95% CI 0.5-3.7). CONCLUSIONS: The study shows an increased risk in mothers who drink >/=3 die units alcohol in pregnancy of preterm births.     

Alcohol drinking and risk of small for gestational age birth

OBJECTIVE: To assess if alcohol drinking is a risk factor for small for gestational age (SGA) birth. METHODS: Case-control study. Cases were 555 women (mean age 31 years, range 16-43) who delivered SGA babies at the Clinica Luigi Mangiagalli and the Obstetric and Gynecology Clinic of the University of Verona. The controls were 1966 women (mean age 31 years, range 14-43) who gave birth at term (> or =37 weeks of gestation) to healthy infants of normal weight at the hospitals where cases had been identified. RESULTS: No increase in the risk of SGA birth was observed in women drinking one or two drinks/day in pregnancy, but three or more per day increased the risk: odds ratios (OR) were 3.2 (1.7-6.2) for > or =3 drinks during the first trimester, 2.7 (1.4-5.3) during the second and 2.9 (1.5-5.7) during the third. CONCLUSIONS: The study shows an increased risk of SGA births in mothers who drink > or =3 units/day of alcohol in pregnancy.     

Association between trihalomethane concentrations in drinking water and adverse pregnancy outcome in Taiwan

Chlorination has been the major strategy for disinfection of drinking water in Taiwan. Recently there has been interest in the relationship between by-products of disinfection of drinking water and pregnancy outcomes including low birth weight and preterm delivery. We performed a study to examine the effects of exposure to total trihalomethanes (TTHMs) on the risk of term low birth weight (TLBW), small for gestational age (SGA), and preterm delivery in Taiwan. TTHMs data were available for 65 municipalities in Taiwan. The study population comprised 90,848 women residing in the 65 municipalities who had a first parity singleton birth between January 1, 2000 and December 31, 2002, and for which complete information on maternal age, education, gestational age, birth weight, and sex of the baby were available. Maternal TTHMs exposure was estimated from the TTHMs concentration for the municipality of residence at birth. The study results provide no evidence of an increased risk of TLBW, SGA, and preterm delivery at the relatively low concentrations of TTHMs in Taiwan's drinking water.     

Patterns of alcohol use before and during pregnancy and the risk of small-for-gestational-age birth

Few studies have examined the effect of binge drinking on human fetal growth. The authors studied the effect of binge drinking 3 months before pregnancy and during the last 3 months of pregnancy on small-for-gestational-age (SGA) birth, using data from the Pregnancy Risk Assessment Monitoring System (PRAMS). PRAMS is an ongoing US survey of women who recently delivered a liveborn infant. Data are collected 2-6 months after birth by using mailed, self-administered questionnaires, with telephone interviews conducted for nonresponders. This study included 50,461 women who delivered at term from 1996 to 1999. Overall, binge drinkers before pregnancy were less likely than nondrinkers to have an SGA birth, but moderate or heavy drinkers (>or=4 drinks per week) who also binged were 2.2 times more likely to have an SGA birth. Moderate and heavy drinkers in late pregnancy were also more likely to have an SGA birth, but there were only 46 women in these categories, so estimates were imprecise. Vascular effects of alcohol or dietary differences between drinkers and nondrinkers may explain the lower risk of SGA birth among some drinkers. The relation of these areas with fetal growth needs more research.     

Preconception homocysteine and B vitamin status and birth outcomes in Chinese women

BACKGROUND: The associations between homocysteine, B vitamin status, and pregnancy outcomes have not been examined prospectively. OBJECTIVE: We assessed the associations of preconception homocysteine and B vitamin status with preterm birth and birth of low-birth-weight (LBW) and small-for-gestational-age (SGA) infants in Chinese women. DESIGN: This was a case-control study of women aged 21-34 y. Preterm cases (n = 29) delivered living infants at <37 wk gestation; term controls (n = 405) delivered infants at > or =37 wk. LBW cases (n = 33) had infants weighing <2500 g; normal-birth-weight controls (n = 390) had infants weighing > or =2500 g. SGA cases (n = 65) had infants below the 10th percentile of weight-for-gestational-age; appropriate-for-gestational-age controls (n = 358) had infants above this cutoff. Nonfasting plasma concentrations of homocysteine, folate, and vitamins B-6 and B-12 were measured before conception. RESULTS: Elevated homocysteine (> or =12.4 micro mol/L) was associated with a nearly 4-fold higher risk of preterm birth (OR: 3.6; 95% CI: 1.3, 10.0; P < 0.05). The risk of preterm birth was 60% lower among women with vitamin B-12 > or =258 pmol/L than among vitamin B-12-deficient women (OR: 0.4; 95% CI: 0.2, 0.9; P < 0.05) and was 50% lower among women with vitamin B-6 > or =30 nmol/L than among vitamin B-6-deficient women (OR: 0.5; 95% CI: 0.2, 1.2; NS). Folate status was not associated with preterm birth, and homocysteine and B vitamin status were not associated with LBW or SGA status. CONCLUSIONS: Elevated homocysteine and suboptimal vitamin B-12 and B-6 status may increase the risk of preterm birth. These results need to be confirmed in larger prospective studies.     

Coffee drinking and risk of preterm birth

OBJECTIVES: We analysed the association between coffee drinking before and during the three trimesters of pregnancy and the risk of preterm birth of babies normal for gestational age (NGA) or small for gestational age (SGA). METHODS: Case-control study conducted in University clinics of North Italy. Cases were 502 women who delivered at <37 weeks of gestation. The controls included 1966 women who gave birth at term (>or=37 weeks of gestation) to healthy infants on randomly selected days at the hospitals where cases had been identified. RESULTS: There was inverse association for coffee consumption in the third trimester of pregnancy in SGA cases compared to NGA (heterogeneity test between OR: chi1(2)=5.6811 P<0.05). In comparison with not drinkers, all the ORs of overall intake of caffeine were closed near the unity for both SGA and NGA preterm birth. CONCLUSION: Compared with no consumption, a low consumption of coffee during pregnancy may not have significant effects on preterm birth.     

Weight gain during pregnancy and the black-white disparity in preterm birth

PurposeTo quantify the relationship between pregnancy weight gain with early and late preterm birth and evaluate whether associations differed between non-Hispanic (NH) black and NH white women.MethodsWe analyzed a retrospective cohort of all live births to NH black and NH white women in the United States 2011–2015 (n = 10,714,983). We used weight gain z-scores in multiple logistic regression models stratified by prepregnancy body mass index (BMI) and race to calculate population attributable risk (PAR) percentages for the contribution of high and low pregnancy weight gain to early and late preterm birth.ResultsPregnancy weight gain was related to early and late preterm birth, but associations varied by BMI and race. For early preterm birth, the PAR percentage for high pregnancy weight gain ranged from 8 to 10% in NH black women and from 6 to 8% in NH white women. There was little evidence of racial differences in late preterm birth: PAR percentages ranged from 2 to 7% in NH black women and from 3 to 7% in NH white women.ConclusionsModerate gestational weight gain is associated with lower rate of preterm birth, with greatest reductions for early preterm birth in NH black women.     

Maternal coffee drinking in pregnancy and risk of small for gestational age birth

OBJECTIVE: We have analysed the association between coffee drinking before and during the three trimesters of pregnancy and risk of small for gestational age (SGA) birth. METHODS: Cases were 555 women who delivered SGA births (ie <10th percentile according Italian standard). The controls included 1966 women who gave birth at term (>/=37 weeks of gestation) to healthy infants of normal weight. RESULTS: In comparison with nondrinkers, the ORs for SGA birth were 1.3 (95% confidence interval, CI, 0.9-1.9) for consumption of four or more cups of coffee/day before pregnancy, and 1.2 (95% CI 0.8-1.8), 1.2 (95% CI 0.8-1.8) and 0.9 (95% CI 0.6-1.4) for consumption of three or more cups of coffee/day during the first, second and third trimester of pregnancy, respectively. CONCLUSION: These findings were consistent in women who delivered preterm and at term births and were not affected by potential confounding such as smoking.     

Risk factors for preterm, low birth weight and small for gestational age birth in urban Aboriginal and Torres Strait Islander women in Townsville

OBJECTIVES: To assess the characteristics of Indigenous births and to examine the risk factors for preterm (<37 weeks), low birth weight (<2,500 g) and small for gestational age (SGA) births in a remote urban setting. DESIGN: Prospective cohort of singleton births to women attending Townsville Aboriginal and Islander Health Services (TAIHS) for shared antenatal care between 1 January 2000 and 31 December 2003. MAIN OUTCOME MEASURES: Demographic, obstetric, and antenatal care characteristics are described. Risk factors for preterm birth, low birth weight and SGA births are assessed. RESULTS: The mean age of the mothers was 25.0 years (95% CI 24.5-25.5), 15.8% reported hazardous or harmful alcohol use, 15.1% domestic violence, 30% had an inter-pregnancy interval of less than 12 months and 9.2% an unwanted pregnancy. The prevalence of infection was 50.2%. Predictors of preterm birth were a previous preterm birth, low body mass index (BMI) and inadequate antenatal care, with the subgroup at greatest risk of preterm birth being women with a previous preterm birth and infection in the current pregnancy. Predictors of a low birth weight birth were a previous stillbirth, low BMI and an interaction of urine infection and non-Townsville residence; predictors of an SGA birth were tobacco use, pregnancy-induced hypertension and interaction of urine infection and harmful alcohol use. CONCLUSION: The prevalence of demographic and clinical risk factors is high in this group of urban Indigenous women. Strategies addressing potentially modifiable risk factors should be an important focus of antenatal care delivery to Indigenous women and may represent an opportunity to improve perinatal outcome in Indigenous communities in Australia.     

Previous Adverse Outcome of Term Pregnancy and Risk of Preterm Birth in Subsequent Pregnancy

Objective Evaluate risk of preterm birth (PTB, < 37 completed weeks’ gestation) among a population of women in their second pregnancy with previous full term birth but other adverse pregnancy outcome. Methods The sample included singleton live born infants between 2007 and 2012 in a birth cohort file maintained by the California Office of Statewide Health Planning and Development. The sample was restricted to women with two pregnancies resulting in live born infants and first birth between 39 and 42 weeks’ gestation. Logistic regression was used to calculate the risk of PTB in the second birth for women with previous adverse pregnancy outcome including: small for gestational age (SGA) infant, preeclampsia, placental abruption, or neonatal death (≤ 28 days). Risks were adjusted for maternal factors recorded for second birth. Results The sample included 133,622 women. Of the women with any previous adverse outcome, 4.7% had a PTB while just 3.0% of the women without a previous adverse outcome delivered early (relative risk adjusted for maternal factors known at delivery 1.4, 95% CI 1.3–1.5). History of an SGA infant, placental abruption, or neonatal death increased the adjusted risk of PTB in their second birth by 1.5–3.7-fold. History of preeclampsia did not elevate the risk of a preterm birth in the subsequent birth. Conclusions for Practice The findings indicate that women with previous SGA infant, placental abruption, or neonatal death, despite a term delivery, may be at increased risk of PTB in the subsequent birth. These women may be appropriate participates for future interventions aimed at reduction in PTB.

     

Relationship of perfluorooctanoic Acid exposure to pregnancy outcome based on birth records in the mid-ohio valley

Background: Perfluorooctanoic acid (PFOA) is a potential cause of adverse pregnancy outcomes, but previous studies have been limited by low exposures and small study size.Objectives: Using birth certificate information, we examined the relation between estimated PFOA exposure and birth outcomes in an area of West Virginia and Ohio whose drinking water was contaminated by a chemical plant.Methods: Births in the study area from 1990 through 2004 were examined to generate case groups of stillbirth (n = 106), pregnancy-induced hypertension (n = 224), preterm birth (n = 3,613), term low birth weight (n = 918), term small-for-gestational-age (SGA) (n = 353), and a continuous measure of birth weight among a sample of term births (n = 4,534). A 10% sample of term births ≥ 2,500 g were selected as a source of controls (n = 3,616). Historical estimates of serum PFOA were derived from a previously developed fate and transport model. In a second study, we examined 4,547 area births linked to a survey with residential history data.Results: In the analysis based only on birth records, we found no consistent evidence of an association between estimated PFOA exposure and stillbirth, pregnancy-induced hypertension, preterm birth, or indices of fetal growth. In the analysis of birth records linked to the survey, PFOA was unrelated to pregnancy-induced hypertension or preterm birth but showed some suggestion of an association with early preterm birth. Measures of growth restriction showed weak and inconsistent associations with PFOA.Conclusions: Based on the analysis using the health survey, these results provide little support for an effect of PFOA exposure on most pregnancy outcomes, except for early preterm birth and possibly fetal growth restriction.     

Mate drinking during pregnancy and risk of preterm and small for gestational age birth

Mate, a hot infusion of Ilex paraguayensis, is a beverage largely consumed in Southeast Latin America, including during pregnancy. To assess the effect of mate drinking during pregnancy on preterm and small for gestational age (SGA) birth, a cross-sectional study was done. From January 1st to December 31st, 1993, in the first 24 h after delivery, all 5304 mothers giving birth at the hospitals in Pelotas, Southern Brazil, were interviewed and several of their characteristics were gathered. Birthweight was recorded and gestational age at birth assessed using the Dubowitz score. All 5189 single births were analyzed. The prevalence of SGA and preterm birth was 8.0 and 9.1%, respectively. Mate intake at least once a week during the entire pregnancy period was reported by approximately 68% of the mothers. Crude analyses showed a 30% increase in the risk of SGA among daily mate drinkers compared with nonconsumers (prevalence ratio = 1.3; 95% CI 1.1-1.6), whereas no statistical association was detected with preterm births. After controlling for confounders, the significance of the association with SGA birth no longer held and the lack of association with prematurity remained unchanged. In conclusion, prevalence of daily mate drinking was high among pregnant women and, contrary to the hypothesis, no harmful effect on intrauterine growth or duration of pregnancy was detected.     

Maternal stress and preterm birth

This study examined a comprehensive array of psychosocial factors, including life events, social support, depression, pregnancy-related anxiety, perceived discrimination, and neighborhood safety in relation to preterm birth (<37 weeks) in a prospective cohort study of 1,962 pregnant women in central North Carolina between 1996 and 2000, in which 12% delivered preterm. There was an increased risk of preterm birth among women with high counts of pregnancy-related anxiety (risk ratio (RR) = 2.1, 95% confidence interval (CI): 1.5, 3.0), with life events to which the respondent assigned a negative impact weight (RR = 1.8, 95% CI: 1.2, 2.7), and with a perception of racial discrimination (RR = 1.4, 95% CI: 1.0, 2.0). Different levels of social support or depression were not associated with preterm birth. Preterm birth initiated by labor or ruptured membranes was associated with pregnancy-related anxiety among women assigning a high level of negative impact weights (RR = 3.0, 95% CI: 1.7, 5.3). The association between high levels of pregnancy-related anxiety and preterm birth was reduced when restricted to women without medical comorbidities, but the association was not eliminated. The prospective collection of multiple psychosocial measures on a large population of women indicates that a subset of these factors is associated with preterm birth.     

Maternal education and adverse birth outcomes among immigrant women to the United States from Eastern Europe: a test of the healthy migrant hypothesis

Immigrant women to the U.S. often have more favorable birth outcomes than their native-born counterparts, including lower rates of preterm birth and low birth weight, a phenomenon commonly attributed to a healthy migrant effect. However, this effect varies by ethnicity and country of origin. No previous study has examined birth outcomes among immigrants from the post-Communist countries of Eastern Europe, a group which includes both economic migrants and conflict refugees. Using data on 253,363 singletons births from New York City during 1995-2003 we examined the risk of preterm birth (PTB) (<37 weeks) or delivering a term small-for-gestational-age (SGA) infant among immigrants from Russia and Ukraine (RU), Poland, and former Yugoslavia Republics (FYR) relative to US-born non-Hispanic whites (NHW). Women in all three Eastern European groups had significantly later entry into prenatal care, were more likely to be Medicaid recipients, and had lower educational attainment than US-born NHW. In binomial regression analyses adjusting for age, education, parity, and pre-pregnancy weight, women from RU and FYR had lower risk of PTB than US-born NHW, whereas women from Poland had similar risk. Lower SGA risk was found among women from Poland and FYR, but not RU. When stratified by education, women with <12 years of education from all Eastern European groups had a reduced risk of PTB relative to US-born NHW. An educational gradient in PTB and SGA risk was less pronounced in all Eastern European groups compared to US-born NHW. The healthy migrant effect is present among immigrants from Eastern Europe to the U.S., especially among women with less education and those from the former Yugoslavia, a group that included many conflict refugees.     

预防低出生体重儿的孕期护理探索

目的:探索预防低出生体重儿的孕期护理。方法:183例产妇,在产后24h对其进行问卷调查有关家庭、社会、经济情况及人口学特征,同时摘录相关孕期检查记录卡;对早产儿组低出生体重儿54例、足月小样儿组低出生体重儿26例、对照组103例进行病例对照研究。结果:3组中,早产组出生体重最低,早产是低出生体重的主要原因;早产组在各阶段的胎头双顶径均>足月小样儿组,且在35周前均不<对照组;足月小样儿组在29周以后越来越<对照组,本研究显示其差距呈波动性。各孕周孕妇体重与基础体重之间增加的情况显示,早产组各阶段一直处于最低,SGA组次之,对照组增加最多。结论:从孕期护理预防低出生体重儿,重点是预防早产儿的发生;关注B超预测与胎婴儿实际体重间的密切相关性是孕期护理不可忽视的工作;做好基础体重的测量与记录,把每次孕妇体重增加情况与基础体重比较,发现低于本研究中对照组增加幅度的,可及时给予孕期营养指导。     

Drinking water contaminants and adverse pregnancy outcomes: a review

Concern for exposures to drinking water contaminants and their effects on adverse birth outcomes has prompted several studies evaluating chlorination disinfection by-products and chlorinated solvents. Some of these contaminants are found to be teratogenic in animal studies. This review evaluates 14 studies on chlorination disinfection by-products such as trihalomethanes (THMs) and five studies on chlorinated solvents such as trichloroethylene (TCE). The adverse birth outcomes discussed in this review include small for gestational age (SGA), low birth weight, preterm birth, birth defects, spontaneous abortions, and fetal deaths. Because of heterogeneities across the studies in the characterization of birth outcomes, the assessment and categorization of exposures, and the levels and mixtures of contaminants, a qualitative review was conducted. Generally, the chief bias in these studies was exposure misclassification that most likely underestimated the risk, as well as distorted exposure-response relationships. The general lack of confounding bias by risk factors resulted from these factors not being associated with drinking water exposures. The studies of THMs and adverse birth outcomes provide moderate evidence for associations with SGA, neural tube defects (NTDs), and spontaneous abortions. Because fewer studies have been conducted for the chlorinated solvents than for THMs, the evidence for associations is less clear. Nevertheless, the findings of excess NTDs, oral clefts, cardiac defects, and choanal atresia in studies that evaluated TCE-contaminated drinking water deserve follow-up.     

Investigating socio-economic disparities in preterm birth: evidence for selective study participation and selection bias

Selective study participation can theoretically lead to selection bias. We explored this issue in the context of a multicentre cohort study of socio‐economic disparities in preterm birth. Women with singleton pregnancies were recruited from four large Montreal maternity hospitals and invited to return for an interview, vaginal examination and venepuncture at 24–26 weeks of gestation. We compared the observed preterm birth rate (ultrasound confirmed) among the 5146 cohort women to that expected based on all 108 724 Montreal Census Metropolitan Area (CMA) singleton births for 1998–2000. The observed preterm birth rate in the study cohort was 5.1%, compared with 6.3% in the CMA (P < 0.001) (unadjusted morbidity ratio [95% CI] = 0.80 [0.71, 0.90]). Within each stratum of maternal education and neighbourhood income (the latter based on postal code matched links to the 2001 Canadian census), cohort women had substantially lower rates of preterm birth than women from the CMA. No significant association between socio‐economic status (SES) and preterm birth was observed in the study cohort, except among ‘indicated’ (non‐spontaneous) cases. The association between neighbourhood income and preterm birth was biased to the null in the study cohort, with adjusted odds ratios in the poorest vs. richest quintiles of 1.01 [0.63, 1.64] in the cohort vs. 1.28 [1.18, 1.39] in the CMA, although no such bias was observed for the association with maternal education assessed at the individual level. We speculate that the lower‐than‐expected preterm birth rate and attenuated association between neighbourhood income and preterm birth may be related to selective participation by women more psychologically invested in their pregnancies. Investigators should consider the potential for biased associations in pregnancy/birth cohort studies, especially associations based on SES or race/ethnicity, and carry out sensitivity analyses to gauge their effects.     

孕早期亚临床甲状腺功能减退及年龄与早产的相关性研究

目的分析年龄及孕早期亚临床甲减(SCH)与早产及其亚型的相关性,为不同年龄孕早期亚甲减患者孕期监测制定个体化策略提供科学依据。方法以2016年2月-2018年6月在甘肃省妇幼保健院高危产科产检的单胎活产孕妇2 868例为研究对象,使用Logistic回归模型分别分析年龄及孕早期亚甲减与早产的相关性。结果控制混杂因素后,与适龄孕妇相比,高龄孕妇(≥35岁)发生早产风险增加0.67倍(OR=1.67,95%CI:1.32～2.13);年龄较小孕妇发生早期/极早期早产风险升高2.65倍(OR=3.65,95%CI:2.21～6.05)。与甲功正常孕妇相比,亚甲减孕妇发生早产风险增加2.07倍(OR=3.07,95%CI:2.28～4.12)、发生中晚期早产风险增加1.67倍(OR=2.67,95%CI:1.86～3.83)。交互作用分析显示,年龄与亚临床甲减对早产的发生风险存在相乘的交互作用。结论不同年龄亚甲减孕妇发生早产及其亚型的风险不一致。建议对孕早期亚甲减患者应根据年龄进行风险分层,开展个体化孕期管理和用药指导。     

母亲出生体重与新生儿出生体重的关系研究

目的 探讨母亲出生体重与新生儿出生体重的关系,以便为研究母亲宫内发育不良对子代发育的影响提供线索。方法 通过巢式病例对照研究,采用多重线性回归分析了解母亲出生体重与新生儿出生体重的关系,并以非条件Logistic回归分析进一步探讨母亲出生体重对小于胎龄儿（small for gestational age,SGA）、大于胎龄儿（large for gestational age,LGA）的影响。结果 SGA的发生率为7.04%,LGA发生率为14.65%。多重线性回归分析结果显示,母亲出生体重与新生儿出生体重呈正相关,母亲出生体重每增加1 kg,新生儿出生体重增加174 g（β=0.174,95% CI:0.134~0.213）。随母亲出生体重的增加,SGA发生率递减（χ_趋势2=13.791,P<0.001）,LGA的发生率递增（χ_趋势2=7.900,P=0.005）,母亲低出生体重（<2 500 g）是SGA的危险因素（OR=2.458,95% CI:1.333~4.534）;以孕期增重分层分析后,结论一致,但出生体重较低的孕妇（＜2 500 g）孕期增重不足会导致SGA发生风险增高。结论 孕妇出生体重低是分娩SGA的危险因素,随着孕妇出生体重增加,新生儿出生体重增大,但未发现LGA与孕妇出生体重有关。     

The Association of Gestational Weight Gain with Birth Weight in Obese Pregnant Women by Obesity Class and Diabetic Status: A Population-Based Historical Cohort Study

Small-for-gestational-age (SGA) and large-for-gestational-age (LGA) infants are associated with increased adverse outcomes. While studies have estimated the association of gestational weight gain with birth weight in obese women, estimates are lacking by obesity class and diabetic status. A population-based historical cohort study of 66,010 obese pregnant women in Missouri delivering liveborn, singleton, term infants in 2002–2008 was conducted. Adjusted odds ratios for SGA and LGA infants were calculated for gestational weight gain categories with multiple logistic regression using the revised Institute of Medicine (IOM) recommended 11–20 pounds as the reference group. A weight gain of 3–10 pounds was not significantly associated with an increased risk of an SGA infant compared to 11–20 pounds in 5/6 obesity class/diabetic status combinations. The exception was Class I Obese non-diabetic women (adjusted odds ratio = 1.28, 95 % confidence interval 1.07, 1.52). When lower amounts of weight gain were considered, diabetic women who gained ≤2 pounds (including women who lost weight) did not have a significantly increased risk of an SGA infant compared to diabetic women who gained 11–20 pounds in any obesity class. Weight gains less than 11–20 pounds were significantly associated with a decreased risk of an LGA infant in 5/6 obesity class/diabetic status combinations. Weight gains lower than the IOM recommendation of 11–20 pounds during pregnancy for obese women generally were significantly associated with decreased risk of LGA infants without being significantly associated with increased risk of SGA infants and differed by obesity class and diabetic status.