Smoking during pregnancy and preterm birth according to obstetric history: French national perinatal surveys

The relation between smoking and preterm delivery is not totally known. Our aim was to determine whether smoking during pregnancy was associated with preterm birth among women at different risk according to their obstetric history. The study was based on data from the 1998 French national perinatal survey. Of the 13073 singleton live births, 4.7% were preterm; 15% of the pregnant women were moderate (one to nine cigarettes per day) and 10% heavy smokers (at least 10 cigarettes per day). Smoking heavily was related to preterm birth (crude odds ratio [OR] = 1.35, 95% confidence interval [95% CI]: [1.04, 1.74]). Multivariable logistic regression showed a relation between smoking and preterm birth among multiparae without previous adverse pregnancy outcomes; the associated adjusted ORs (AORs) were 1.25 [95% CI 0.83, 1.87] among moderate smokers and 1.46 [95% CI 0.98, 2.20] among heavy smokers. The corresponding AORs were 0.69 [95% CI 0.46, 1.05]) and 0.96 [95% CI 0.59, 1.56] for primiparae and 1.11 [95% CI 0.63, 1.93] and 0.50 [95% CI 0.25, 0.98] for multiparae with previous adverse pregnancy outcomes. Our study showed a relation between heavy smoking during pregnancy and preterm birth mostly for women with low obstetric risk.     

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.     

早产影响因素的前瞻性队列研究

目的 分析中国早产的流行现状及危险因素,为早产的预防提供参考依据.方法 本研究数据来源于中国孕产妇队列研究.协和项目(Chinese Pregnant Women Cohort Study,CP-WCS),通过问卷调查和医院信息系统(hospital information system,HIS)收集孕妇基本情况和分娩...     

Insufficient weight management in pregnant women with gestational diabetes mellitus

ObjectivesThis study investigated whether weight was managed appropriately in pregnant women with gestational diabetes mellitus (GDM) and examined the association between insufficient gestational weight gain (GWG) and adverse pregnancy outcomes.Methods The study included 235 pregnant women with GDM from the Korean Pregnancy Outcome Study. GWG from the second to the third trimester (kg/wk ) and total GWG (kg) were classified as insufficient, appropriate, or excessive according to the 2009 Institute of Medicine guidelines. Adverse pregnancy outcomes included maternal (hypertensive disorders of pregnancy, preterm birth, cesarean delivery, and delivery complications) and infant (low birth weight, high birth weight, neonatal intensive care unit admission, and congenital anomalies) outcomes.Results The proportion of pregnant women with GDM who had insufficient GWG from the second to the third trimester was 52.3%, and that of participants with total insufficient GWG was 48.1%. There were no significant associations between insufficient GWG from the second to the third trimester and adverse pregnancy outcomes. Participants with total insufficient GWG had a significantly lower risk of preterm birth (odds ratio [OR], 0.17; 95% confidence interval [CI], 0.05–0.60) and high birth weight (OR, 0.23; 95% CI, 0.07–0.80).Conclusion Our findings suggest the importance of appropriate weight management and the need for GWG guidelines for pregnant women with GDM.     

Is conception delay a risk factor for reduced gestation or birthweight?

Previous studies have suggested an association between delays in conception and adverse perinatal outcomes, specifically, low birthweight and preterm birth. We investigated the relationship between conception delay (defined as >6 months to become pregnant) and three perinatal outcomes: low birthweight (LBW; <2500 g), preterm birth (PTB; <37 weeks), and small-for-gestational-age (SGA; <10th percentile weight for given gestational age) using data from the Collaborative Perinatal Project. The study cohort was limited to pregnancies with a known time-to-pregnancy (n = 8465; 15%). Generalised estimating equations were used to estimate odds ratios (OR) and 95% confidence intervals [CI] for risk of adverse perinatal outcomes accounting for the clustering of pregnancy outcomes for women with more than one pregnancy. After adjusting for confounders, all ORs were close to the null (LBW, OR = 1.01; 95% CI = 0.86, 1.20), (PTB, OR = 1.10; 95% CI = 0.95, 1.27), (SGA, OR = 1.06; 95% CI = 0.91, 1.25). Thus, we found no evidence to support an adverse relationship between conception delay and decrements in gestation or birthweight among this select sample of fertile women, even after varying the cut-point for defining conception delay.     

Maternal acute respiratory infectious diseases during pregnancy and birth outcomes

The objective of the study was to evaluate the possible association between maternal acute respiratory infectious diseases (ARID) during pregnancy and birth outcomes. Newborn infants born to mothers with or without ARID as reference were compared in the population-based large data set of newborns without any defect in the Hungarian Case–Control Surveillance System of Congenital Abnormalities. Main outcome measures were birth weight and gestational age at delivery, in addition the rate of preterm births and low birthweight newborns. Of 38,151 newborns, 3,455 (9.1%) had mothers with ARID during pregnancy which were differentiated according to six manifestations from sinusitis to the pneumonia. Mothers with ARID in pregnancy had a longer (0.3 week) gestational age at delivery (adjusted t = 5.4; p < 0.0001) and a lower rate of preterm births (6.7% vs. 9.4%) [adjusted odds ratio (OR) with 95% confidence interval (CI): 0.72, 0.63–0.83] than mothers without ARID. However, severe ARID (bronchitis–bronchiolitis and particularly pneumonia) associated with a higher rate of preterm births (13.0%, adjusted OR with 95% CI: 1.4, 1.1–1.8), while mild ARID (sinusitis, pharyngitis, tonsillitis, laryngitis–tracheitis) resulted in a lower rate of preterm births (5.5%, adjusted OR with 95% CI: 0.5, 0.4–0.7). In conclusion, there was an obvious correlation between severity of ARID in pregnant women and rate of preterm births.     

孕期被动吸烟对妊娠并发症及妊娠结局的影响

目的了解孕期被动吸烟发生情况,并探讨其对妊娠并发症及结局的影响。方法选取2012年4月―2013年3月在我国15家医疗保健机构分娩的8926例单胎活产产妇作为研究对象,使用自制调查问卷收集孕期被动吸烟发生情况、妊娠并发症和结局等信息,采用单因素和多因素Logistic回归分析模型分析孕期被动吸烟对妊娠并发症及结局的影响。结果共1801例产妇在孕期经历被动吸烟。控制混杂因素后,孕期经历被动吸烟的产妇妊娠期糖尿病(gestational diabetes mellitus,GDM)的发生风险是非被动吸烟者的1.359倍(95%CI:1.146~1.612,P<0.001),胎膜早破的风险为1.290倍(95%CI:1.095~1.520,P=0.002),早产的风险为1.367倍(95%CI:1.155~1.619,P<0.001),娩出低出生体重儿的风险为1.341倍(95%CI:1.079~1.668,P=0.008)。与非被动吸烟者相比,平均每周被动吸烟天数≥4天者胎膜早破、早产和低出生体重儿的发生风险分别为非被动吸烟者的1.402倍(95%CI:1.104~1.780,P=0.006)、1.690倍(95%CI:1.339~2.132,P<0.001)和1.584倍(95%CI:1.172~2.141,P=0.023)。结论被调查产妇孕期被动吸烟率较高,孕期经历被动吸烟能够增加妊娠期糖尿病、胎膜早破、早产和低出生体重儿的发生风险。     

孕期环境暴露对早产和低出生体重影响的队列研究

  目的  探讨中国孕妇孕期环境暴露和新生儿早产及低出生体重的关系。  方法  采用自行设计的孕期环境暴露调查问卷,问卷内容包括被动吸烟、通风情况、装修情况、臭水沟、垃圾站、化工厂、高温、辐射、噪声和粉尘等环境暴露因素,对中国孕产妇队列研究项目中的孕妇进行问卷调查,随访收集新生儿的出生情况。关联性分析采用Logistic回归分析模型。  结果  本研究以6 189名孕妇为研究对象,其中283名(4.57%)孕妇早产,分娩202名(3.26%)低出生体重儿,调整年龄、民族、户口、文化程度、职业、家庭年收入、孕前体重指数(body mass index,BMI)以及产次等因素后,Logistic回归分析模型分析显示,与未接触噪声的孕妇相比,孕妇孕期在工作或居家环境中暴露于噪声环境更容易发生早产(OR=1.668,95% CI:1.197~2.323);与未接触高温的孕妇相比,孕期在工作或居家环境中暴露于高温环境的孕妇更容易发生早产(OR=2.237,95% CI:1.171~4.274)。尚未发现其他环境暴露因素与早产和低出生体重的相关性。  结论  孕期暴露于噪声和高温环境是孕妇早产的危险因素。积极开展健康宣教,减少孕妇孕期在生活工作环境中的噪声和高温暴露,可能有助于降低早产的发生风险。     

Moderate alcohol consumption during pregnancy and the risk of low birth weight and preterm birth. The generation R study

PURPOSE: To examine the associations of alcohol consumption in different periods of pregnancy with the risks of low birth weight and preterm birth. METHODS: This study was based on 7141 subjects participating in a population-based prospective cohort study from early pregnancy. Alcohol consumption was assessed in early, mid, and late pregnancy. Birth outcomes were birth weight in grams, low birth weight (<2500 g), small size for gestational age at birth (< -2 standard deviation scores) and preterm birth (gestational age <37 weeks). RESULTS: Overall, alcohol consumption during pregnancy was not associated with adverse birth outcomes. However, dose-response analyses showed tendencies toward adverse effects of average consumption of 1 or more alcoholic drinks per day in early pregnancy on birth weight (difference -129 g [95% confidence interval (CI): -271, 12]), low birth weight (adjusted odds ratio [aOR] 4.81 [95% CI: 1.10, 21.08]), small size for gestational age at birth (aOR 1.45 [95% CI: 0.33, 6.44]) and preterm birth (aOR 2.51 [95% CI: 0.92, 6.81]). Similar effects were found in late pregnancy. CONCLUSION: Average consumption of one or more but not less than one alcoholic drink per day in early or late pregnancy seems to be associated with adverse birth outcomes in the offspring.     

Nutritional indicators of adverse pregnancy outcomes and mother-to-child transmission of HIV among HIV-infected women

BACKGROUND: Poor nutrition may be associated with mother-to-child transmission (MTCT) of HIV and other adverse pregnancy outcomes. OBJECTIVE: The objective was to examine the relation of nutritional indicators with adverse pregnancy outcomes among HIV-infected women in Tanzania, Zambia, and Malawi. DESIGN: Body mass index (BMI; in kg/m(2)) and hemoglobin concentrations at enrollment and weight change during pregnancy were prospectively related to fetal loss, neonatal death, low birth weight, preterm birth, and MTCT of HIV. RESULTS: In a multivariate analysis, having a BMI < 21.8 was significantly associated with preterm birth [odds ratio (OR): 1.82; 95% CI: 1.34, 2.46] and low birth weight (OR: 2.09; 95% CI: 1.41, 3.08). A U-shaped relation between weight change during pregnancy and preterm birth was observed. Severe anemia was significantly associated with fetal loss or stillbirth (OR: 3.67; 95% CI: 1.16, 11.66), preterm birth (OR: 2.08; 95% CI: 1.39, 3.10), low birth weight (OR: 1.76; 95% CI: 1.07, 2.90), and MTCT of HIV by the time of birth (OR: 2.26; 95% CI: 1.18, 4.34) and by 4-6 wk among those negative at birth (OR: 2.33; 95% CI: 1.15, 4.73). CONCLUSIONS: Anemia, poor weight gain during pregnancy, and low BMI in HIV-infected pregnant women are associated with increased risks of adverse infant outcomes and MTCT of HIV. Interventions that reduce the risk of wasting or anemia during pregnancy should be evaluated to determine their possible effect on the incidence of adverse pregnancy outcomes and MTCT of HIV.     

Anxiety and Optimism Associated with Gestational Age at Birth and Fetal Growth

Psychosocial factors such as anxiety or optimism may be related to the risk of adverse pregnancy outcomes, but the evidence is conflicting. We investigated the relation between maternal anxiety, optimism, gestational age and infant birth weight in a cohort of 667 nulliparous women from the Prenatal Exposures and Preeclampsia Prevention study, Pittsburgh PA. Women completed the Spielberger Trait Anxiety Inventory and the Life Orientation Test at 18 weeks gestation. Linear and logistic regression models assessed the relation of anxiety and optimism to gestational age, birth weight centile, preterm delivery (<37 weeks) or small for gestational age (<10th percentile) births. After adjustment for age, race, preeclampsia, and smoking, higher anxiety was associated with decreasing gestational age (−1.6 days per SD increase in anxiety score, P = 0.06). This relationship was modified by maternal race (P < 0.01 for interaction). Among African American women, each SD increase in anxiety was associated with gestations that were, on average, 3.7 days shorter (P = 0.03). African American women with anxiety in the highest quartile had gestations that were 8.2 days shorter, and they had increased risk for preterm birth after excluding cases of preeclampsia (OR 1.69, 95% CI 1.08, 2.64). There was no association between anxiety and gestational age among White women. There was also no relation between anxiety, optimism and birth weight centile. Trait anxiety was associated with a reduction in gestational age and increased risk for preterm birth among African American women. Interventions that reduce anxiety among African American pregnant women may improve pregnancy outcomes.     

Effects of calcium supplementation during pregnancy on maternal, fetal and birth outcomes

Gestational hypertensive disorders are the second leading cause of maternal death worldwide. Epidemiological and clinical studies have shown that an inverse relationship exists between calcium intake and development of hypertension in pregnancy. The purpose of this review was to evaluate preventive effect of calcium supplementation during pregnancy on gestational hypertensive disorders and related maternal and neonatal morbidity and mortality. A literature search was carried out on PubMed, WHOLIS, PAHO and Cochrane Library. Only randomised trials were included in the review. Data were extracted into a standardised Excel sheet. Primary outcomes were pre-eclampsia, preterm birth and birthweight. Other neonatal outcomes such as neonatal mortality, small-for-gestational age and low birthweight were also evaluated. A total of 15 randomised controlled trials were included in this review. Pooled analysis showed that calcium supplementation during pregnancy reduced risk of pre-eclampsia by 52% [relative risk (RR) 0.48; 95% confidence interval (CI) 0.34, 0.67] and that of severe pre-eclampsia by 25% (RR 0.75 [95% CI 0.57, 0.98]). There was no effect on incidence of eclampsia (RR 0.73 [95% CI 0.41, 1.27]). There was a significant reduction for risk of maternal mortality/severe morbidity (RR 0.80 [95% CI 0.65, 0.97]). Calcium supplementation during pregnancy was also associated with a significant reduction in risk of pre-term birth (RR 0.76 [95% CI 0.60, 0.97]). There was an extra gain of 85 g in the intervention group compared with control (mean difference 85 g [95% CI 37, 133]). There was no effect of calcium supplementation on perinatal mortality (RR 0.90 [95% CI 0.74, 1.09]). There was a statistically non-significant increased risk of urolithiasis in the intervention group compared with control (RR 1.52 [95% CI 0.06, 40.67]). In conclusion, calcium supplementation during pregnancy is associated with a reduction in risk of gestational hypertensive disorders and pre-term birth and an increase in birthweight. There is no increased risk of kidney stones.     

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.     

兰州地区早产影响因素的研究

目的 探讨早产、自发性早产和医源性早产的相关高危因素.方法 回顾性调查2010年1月至2012年12月在甘肃省妇幼保健院住院分娩足月儿和早产儿的孕妇的住院资料,分娩足月活产儿5639例、早产儿540例,分为足月产组(≥37周孕龄)和早产组(<37周孕龄),比较早产组和足月产组发生早产的相关危险因素,以及自发性早产和医源性早产的相关高危因素.结果 ①Logistic回归分析发现教育年限(≥16年)(OR=0.61,95%CI:0.48~0.78)、家庭平均月收入(>3000元)(OR=0.62,95%CI:0.50~0.78)是早产发生的保护因素,而母亲妊娠合并症,比如妊娠期糖尿病(GDM)(OR=3.97,95%CI:1.70~9.25)、妊娠期高血压疾病(HDP)(OR=4.43,95%CI:3.35~5.87)、妊娠期胆汁淤积症(ICP)(OR=4.88,95%CI:3.25~7.32)是早产发生的独立高危因素.②按早产的病因分类,本研究中340例为自发性早产儿,余200例为医源性早产.经分层多因素非条件Logistic回归分析表明,与足月产相比,经产妇(OR=2.66,95%CI:1.87~3.76)、GDM(OR=4.52,95%CI:1.42~14.38),尤其是HDP孕妇(OR=14.19,95%CI:10.10~19.93)更易发生医源性早产,而ICP孕妇更多出现自发性流产(OR=12.875,95%CI:12.75~13.00).结论 应及早识别早产潜在的高危因素,加强围生期管理,以减少早产的发生,改善围生儿结局.     

The influence of maternal age on very preterm birth of twins: differential effects by parity

For singleton births, parity can modify the effect of maternal age on birth outcomes such as low birthweight and preterm birth; however, it is unknown whether this relationship exists for twin births. As the rate of twin births increases among older women, it is important to understand how parity may influence the relationship between maternal age and adverse birth outcomes. The NCHS Matched Multiple Birth Data Set, which contains all twin births in the USA from 1995 to 1998, was analysed. Parity was grouped into two levels (primiparous--no prior live births, and multiparous--at least one prior live birth), and maternal age was divided into the following groups: 20-24, 25-29, 30-34, 35-39, and 40 years or more. Very preterm birth was defined as births occurring before 33 weeks. Logistic regression was used to obtain odds ratios (OR) to estimate the risk of very preterm birth, and to determine the relationships between parity, maternal age, and very preterm birth. Among primiparae, women 40 years and older had a reduced risk of very preterm birth compared with women of 25-29 years (OR 0.74 [95% CI=0.66, 0.84]). Among multiparae, women 40 years and older had the same risk of very preterm birth compared with women of 25-29 years (OR 1.00 [95% CI=0.90, 1.12]). However, stratification by education revealed that the age gradient was limited to women with >12 years education among primiparae. The effect of maternal age on very preterm birth of twins differs according to parity. To some extent, that effect is further modified by education. Therefore, future analyses of maternal age and twin birth outcomes should account for measures of obstetric history and other factors, which may influence these results.     

Active and passive maternal smoking during pregnancy and the risks of low birthweight and preterm birth: the Generation R Study

The objective of this study was to examine the associations between active and passive smoking in different periods of pregnancy and changing smoking habits during pregnancy, with low birthweight and preterm birth. The study was embedded in the Generation R Study, a population-based prospective cohort study from early fetal life onwards in Rotterdam, The Netherlands. Active and passive smoking were assessed by questionnaires in early, mid- and late pregnancy. Analyses were based on 7098 pregnant women and their children. Active smoking until pregnancy was ascertained and was not associated with low birthweight and preterm birth. Continued active smoking after pregnancy was also recorded and was associated with low birthweight (adjusted odds ratio 1.75 [95% CI 1.20, 2.56]) and preterm birth (adjusted odds ratio 1.36 [95% CI 1.04, 1.78]). The strongest associations were found for active maternal smoking in late pregnancy. Passive maternal smoking in late pregnancy was associated with continuously measured birthweight (P for trend <0.001). For all active smoking categories in early pregnancy, quitting smoking was associated with a higher birthweight than continuing to smoke. Tendencies towards smaller non-significant beneficial effects on mean birthweight were found for reducing the number of cigarettes without quitting completely. This study shows that active and passive smoking in late pregnancy are associated with adverse effects on weight and gestational age at birth. Smoking in early pregnancy only, seems not to affect fetal growth adversely. Health care strategies for pregnant women should be aimed at quitting smoking completely rather than reducing the number of cigarettes.     

Pre-Pregnancy Body Mass Index and Weight Gain During Pregnancy: Relations with Gestational Diabetes and Hypertension, and Birth Outcomes

To study the relationship between pre-pregnancy body mass index (BMI) and weight gain during pregnancy with pregnancy and birth outcomes, with a focus on gestational diabetes and hypertension and their role in the association with fetal growth. We studied 1,884 mothers and offspring from the Eden mother–child cohort. Weight before pregnancy (W1) and weight after delivery (W2) were collected and we calculated BMI and net gestational weight gain (netGWG = (W2 − W1)/(weeks of gestation)). Gestational diabetes, hypertension gestational age and birth weight were collected. We used multivariate linear or logistic models to study the association between BMI, netGWG and pregnancy and birth outcomes, adjusting for center, maternal age and height, parity and average number of cigarettes smoked per day during pregnancy. High BMI was more strongly related to the risk of giving birth to a large-for-gestational-age (LGA) baby than high netGWG (odds ratio OR [95% CI] of 3.23 [1.86–5.60] and 1.61 [0.91–2.85], respectively). However, after excluding mothers with gestational diabetes or hypertension the ORs for LGA, respectively weakened (OR 2.57 [1.29–5.13]) for obese women and strengthened for high netGWG (OR 2.08 [1.14–3.80]). Low in comparison to normal netGWG had an OR of 2.18 [1.20–3.99] for pre-term birth, which became stronger after accounting for blood pressure and glucose disorders (OR 2.70 [1.37–5.34]). Higher net gestational weight gain was significantly associated with an increased risk of LGA only after accounting for blood pressure and glucose disorders. High gestational weight gain should not be neglected in regard to risk of LGA in women without apparent risk factors.     

Utilisation of prenatal services and birth outcomes: a community-based study in Israel

Summary
The purpose of this paper was to assess several measures of utilisation of prenatal care as predictors of birth outcome in a community where the availability and quality of services were equal for all pregnant women. A case-control study was conducted in a small community in Israel, comparing 189 women whose pregnancy resulted in an unfavourable outcome (perinatal mortality, preterm birth and low birthweight at term) with 384 women, matched by birth order, who had a live, full-term infant weighing 2500 g or more. In a multivariable analysis, adjusting for pregnancy complications, maternal age, parity and socio-economic disadvantage, gestational age at initiation of prenatal care was not an independent predictor of unfavourable outcome; neither was lower than the recommended number of visits for the period under care. However, a higher than expected number of visits was associated with unfavourable outcome [odds ratio (OR)=6.10, 95% CI 2.09–17.78], as was non-compliance with medical recommendations [OR=2.02, 95% CI 1.24–3.29. The context of prenatal care delivery, as well as the process of care and compliance with recommendations, should be assessed in order to determine the impact of prenatal care on birth outcomes.     

Maternal exposure to airborne polychlorinated biphenyls (PCBs) and risk of adverse birth outcomes

Human health effects of airborne lower-chlorinated polychlorinated biphenyls (LC-PCBs) are largely unexplored. Since PCBs may cross the placenta, maternal exposure could potentially have negative consequences for fetal development. We aimed to determine if exposure to airborne PCB during pregnancy was associated with adverse birth outcomes. In this cohort study, exposed women had lived in PCB contaminated apartments at least one year during the 3.6 years before conception or the entire first trimester of pregnancy. The women and their children were followed for birth outcomes in Danish health registers. Logistic regression was performed to estimate odds ratios (OR) for changes in secondary sex ratio, preterm birth, major congenital malformations, cryptorchidism, and being born small for gestational age. We performed linear regression to estimate difference in birth weight among children of exposed and unexposed mothers. All models were adjusted for maternal age, educational level, ethnicity, and calendar time. We identified 885 exposed pregnancies and 3327 unexposed pregnancies. Relative to unexposed women, exposed women had OR 0.97 (95% CI 0.82, 1.15) for secondary sex ratio, OR 1.13 (95% CI 0.76, 1.67) for preterm birth, OR 1.28 (95% CI 0.81, 2.01) for having a child with major malformations, OR 1.73 (95% CI 1.01, 2.95) for cryptorchidism and OR 1.23 (95% CI 0.88, 1.72) for giving birth to a child born small for gestational age. The difference in birth weight for children of exposed compared to unexposed women was ? 32 g (95% CI—79, 14). We observed an increased risk of cryptorchidism among boys after maternal airborne LC-PCB exposure, but due to the proxy measure of exposure, inability to perform dose–response analyses, and the lack of comparable literature, larger cohort studies with direct measures of exposure are needed to investigate the safety of airborne LC-PCB exposure during pregnancy

     

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。