Maternal second-trimester serum ferritin concentrations and subsequent risk of preterm delivery

We studied the relationship between maternal second-trimester serum ferritin concentrations and preterm delivery. The 312 preterm delivery cases, studied in aggregate and in subgroups [spontaneous preterm labour, preterm premature rupture of membranes, medically induced preterm delivery, moderate preterm delivery (gestational age at delivery 34-36 weeks) and very preterm delivery (gestational age at delivery <34 weeks)] were compared with 424 randomly selected women who delivered at term. Maternal ferritin concentrations, measured in serum collected at 17 weeks gestation on average, was determined using a two-site chemiluminometric immunoassay. Using multiple logistic regression, we derived maximum likelihood estimates of adjusted odds ratios (OR) and 95% confidence intervals [CI]. Elevation in maternal second-trimester ferritin was weakly associated with the risk of preterm delivery overall. After adjusting for possible confounding by maternal age, race/ethnicity, parity, Medicaid payment status and smoking during the index pregnancy, the OR for extreme quartiles (>64.5 vs. <26.0 ng/mL) of ferritin was 1.3 [95% CI 0.8, 2.1]. Stratified analyses indicated that elevated maternal serum ferritin was associated with an increased risk of preterm premature rupture of membranes (OR = 2.1; 95% CI 1.1, 4.1), but not with spontaneous preterm labour (OR = 0.9; 95% CI 0.4, 1.7) or medically induced preterm delivery (OR = 1.1; 95% CI 0.6, 2.0). The relationship between elevated maternal second-trimester serum ferritin concentrations and preterm delivery was strongest for spontaneous very preterm deliveries (<34 weeks gestation). Women with ferritin concentrations in the highest decile (>96 ng/mL) experienced a 2.7-fold increased risk of delivering before 34 completed weeks, compared with women with concentrations <26.0 ng/mL. These results are consistent with some previous reports, and further underline the potential for heterogeneity in the aetiology of preterm delivery.     

Racial Differences in the Patterns of Singleton Preterm Delivery in the 1988 National Maternal and Infant Health Survey

Objectives: To determine if the association between race and preterm delivery would persist when preterm delivery was partitioned into two etiologic pathways. Methods: We evaluated perinatal and obstetrical data from the 1988 National Maternal and Infant Health Survey and classified preterm delivery as spontaneous or medically indicated. Discrete proportional hazard models were fit to assess the risk of preterm delivery for Black women compared with White women adjusting for potential demographic and behavioral confounding variables. Results: Preterm delivery occurred among 17.4% of Black births and 6.7% of White births with a Black versus White unadjusted hazard ratio (HR) of 2.8 (95% CI = 2.4–3.3). The adjusted HR for a medically indicated preterm delivery showed no racial difference in risk (HR = 1.0, 95% CI = 0.4–2.6). However, for spontaneous preterm delivery between 20 and 28 weeks gestation, the Black versus White adjusted hazard ratio (HR) was 4.9 (95% CI = 3.4–7.1). Conclusions: Although we found an increased unadjusted HR for preterm delivery among Black women compared with White women, the nearly fivefold increase in adjusted HR for the extremely preterm births and the absence of a difference for medically indicated preterm delivery was unexpected. Given the differences in the risks of preterm birth between Black and White women, we recommend to continue examining risk factors for preterm delivery after separating spontaneous from medically indicated preterm birth and subdividing preterm delivery by gestational age to shed light on the reasons for the racial disparity.     

Defining preterm delivery--the epidemiology of clinical presentation

It is possible that preterm delivery is not a single entity but a cluster of conditions with different aetiologies that ultimately result in the delivery of an infant before 37 completed weeks of gestation. Whereas some researchers have reported aetiological heterogeneity, others have found no differences between subtypes or have disputed the desirability and utility of classifying preterm birth into subtypes. This study explores the relationship of maternal risk factors to type of preterm delivery in a cohort of over 7000 black and white women delivering singleton infants at the University of California, San Francisco's Moffitt Hospital between 1980 and 1990. Although the magnitude of the effect of individual risk factors differed between preterm delivery subtypes, the set of risk factors significantly associated with both categories of spontaneous preterm delivery was identical, while that associated with medically indicated preterm births was different. This study indicates that whereas the distinction between spontaneous preterm deliveries and those that are medically indicated seems valid, distinguishing between types of spontaneous preterm births may not lead to useful aetiological inferences.     

Smoking during pregnancy according to obstetric complications and parity: results of the EUROPOP study

This study aimed to analyse the relationship between smoking and preterm birth (22-36 weeks) according to the main obstetric complications leading to the preterm birth, both overall and by parity. The EUROPOP study is a case-control study carried out between 1994 and 1997; 3,787 preterm and 5,602 full-term births were included, from maternity units in 10 countries, using the same protocol. Social, demographic and medical information was collected after delivery, from obstetric records and interviews with the mothers. Cases were classified according to the main obstetric complication (hypertension, haemorrhage, preterm premature rupture of membranes (PPROM), idiopathic spontaneous preterm labour, intrauterine growth retardation, all other causes). Multiple logistic regression analysis was used to control for confounders. Twenty four percent of cases and 20% of controls were smokers. Smoking during pregnancy, heavy smoking (>or=10 cigarettes per day) in particular, was a risk factor for preterm birth (aOR = 1.39, 95% CI:1.20-1.60). Smoking increased the risk of preterm delivery due to all obstetric complications other than hypertension. For these complications, the risk of preterm delivery associated with smoking was higher for multiparae (aOR = 1.46, 95% CI:1.24-1.71) than for primiparae (aOR = 1.18, 95% CI:1.00-1.38). In conclusion, smoking during pregnancy increases the risk of preterm birth among women with all obstetric complications except hypertension. This association is stronger in multiparae than in primiparae and the risk is higher for heavy smokers.     

Obesity subtypes and risk of spontaneous versus medically indicated preterm births in singletons and twins

Using data from the Missouri maternally linked files (1989-1997), the authors examined the association among maternal obesity, obesity subtypes, and spontaneous and medically indicated preterm (<37 weeks) and very preterm (<33 weeks) births in singletons and twins. Adjusted odds ratios were obtained with correction for intracluster correlation. The prevalence of obesity increased by 77% over the study period (p(trend) < 0.001). Obese mothers had a lower risk for spontaneous preterm birth, and this was more pronounced among twins (odds ratio = 0.68, 95% confidence interval: 0.62, 0.75) than singletons (odds ratio = 0.84, 95% confidence interval: 0.82, 0.87). However, this association was present only among obese women who gained less than 0.69 kg/week for singletons and between 0.23 and 0.69 kg/week for twins. By contrast, obese mothers with singleton gestation had about 50% greater odds of medically indicated preterm (odds ratio = 1.46, 95% confidence interval: 1.39, 1.54) and very preterm (odds ratio = 1.49, 95% confidence interval: 1.34, 1.65) births, and the risk increases with ascending severity of obesity (p(trend) < 0.01). For extreme obesity, the risk of medically indicated preterm and very preterm births was almost double that for nonobese women. Similar findings were observed in twins. These data suggest that obesity increases the risk for medically indicated but not spontaneous preterm birth in both singletons and twins.     

Maternal asthma and risk of preterm delivery

PURPOSE: We studied the relation between maternal history of asthma and preterm delivery. METHODS: The 312 preterm delivery cases, studied in aggregate, and in subgroups (spontaneous preterm labor, preterm premature rupture of membranes, medically induced preterm delivery), were compared with 424 randomly selected women who delivered at term. Maternal medical records provided information on maternal lifetime asthma status, pregnancy outcome, and sociodemographic characteristics. Using multivariate logistic regression, we derived maximum likelihood estimates of adjusted odds ratios (OR) and 95% confidence intervals (CI). RESULTS: Maternal history of asthma was associated with an increased risk of preterm delivery overall (OR = 2.37; 95% CI 1.15-4.88). Analyses of preterm delivery sub-groups indicated that maternal history of asthma was associated with at least a doubling in risk of spontaneous preterm labor (OR = 2.35; 95% CI 0.84-6.58) and medically induced preterm delivery (OR = 2.69; 95% CI 1.11-6.53), though only the latter approached statistical significance. There was some evidence of a modest association between maternal asthma and risk of preterm premature rupture of membranes (OR = 1.63; 95% CI 0.50-5.33). CONCLUSIONS: These results support the hypothesis that maternal asthma is associated with an increased risk of preterm labor and delivery.     

Vaginal bleeding during pregnancy and preterm birth

This study investigated the relation between self-reported vaginal bleeding during pregnancy and preterm birth in a prospective cohort of 2,829 pregnant women enrolled from prenatal clinics between 1995 and 2000 in central North Carolina. The overall association between vaginal bleeding and preterm birth was modest (risk ratio (RR) = 1.3, 95% confidence interval (CI): 1.1, 1.6). Bleeding in the first trimester only was associated with earlier preterm birth (< or =34 weeks' gestation) (RR = 1.6, 95% CI: 1.1, 2.4) and preterm birth due to preterm premature rupture of the membranes (PPROM) (RR = 1.9, 95% CI: 1.1, 3.3). Bleeding in both trimesters was associated with preterm birth due to preterm labor (RR = 3.6, 95% CI: 1.9, 6.8). Bleeding of multiple episodes, on multiple days, and with more total blood loss was associated with an approximate twofold increased risk of earlier preterm birth, PPROM, and preterm labor. In contrast, bleeding in the second trimester only, of a single episode, on a single day, and with less total blood loss was not associated with any category of preterm birth. Vaginal bleeding was not associated with preterm birth among African Amercians (RR = 1.2, 95% CI: 0.9, 1.7). This study indicates that more intense but not less intense bleeding is associated with earlier preterm birth and spontaneous preterm birth presenting as PPROM or preterm labor, and it suggests that bleeding is less predictive of preterm birth among African-American compared with White women.     

Incidence of and socio-demographic risk factors for stillbirth, preterm birth and low birthweight among Zimbabwean women

Data on birth outcomes are important for planning maternal and child health care services in developing countries. Only a few studies have examined frequency of birth outcomes in Zimbabwe, none of which has jointly examined the spectrum of poor birth outcomes across important demographic subgroups. We assessed delivery patterns and birth outcomes in 17 174 births over a one-year period from October 1997 to September 1998 at Harare Hospital, Zimbabwe. The annual rate of stillbirth was 61 per 1000 live births, rate of preterm birth (<37 weeks) was 168 per 1000, and low birthweight (LBW) (<2500 g) was 199 per 1000. Not attending antenatal care (prenatal care) was associated with increased risks of stillbirth [relative risk (RR) = 2.54, 95% CI 2.21, 2.92], preterm delivery [RR = 2.43, 95% CI 2.26, 2.61] and LBW births [RR = 2.16, 95% CI 2.02, 2.31]. Preterm births and LBW births were more likely to be stillborn [RR = 7.26, 95% CI 6.28, 8.39 and RR = 6.85, 95% CI 5.94, 7.91]. In conclusion, the rate of stillbirth is high and is predominantly associated with preterm births and to a lesser extent LBW. Reducing the frequency of stillbirth will require a better understanding of the determinants of preterm births and strategies for addressing this particular subset of high-risk births.     

Delayed childbearing: no evidence for increased risk of low birth weight and preterm delivery

Prior studies of the effect of increased maternal age on reproductive outcome in primiparous women have often ignored the possible influence on this relation of more frequent histories of spontaneous abortion and infertility in older women. When these histories are taken into account, the present study of 1,382 white primiparous women who had live singleton deliveries at Yale-New Haven Hospital finds no evidence for an increased risk of low birth weight (relative risk (RR) = 1.06, 95% confidence interval (CI) = 0.38-2.94) or preterm delivery (RR = 1.07, 95% CI = 0.50-2.24) in women delivering at age 30 years or more compared with younger women. Mean birth weight (beta = -19 g, p = 0.57) and gestational age (beta = -0.16 weeks, p = 0.34) were also not significantly affected by older maternal primiparity. Women aged 35 years or more had twice the rate of preterm births compared with women under age 30, although this result was not statistically significant in this data set (RR = 2.07, 95% CI = 0.67-6.35). Other confounding variables were taken into account.     

Study of environmental, social, and paternal factors in preterm delivery using sibs and half sibs. A population-based study in Denmark

OBJECTIVE: The aim of this study was to evaluate the influence on preterm delivery of changes in putative genetic and environmental risk factors between two consecutive births. Low social status is a suspected risk indicator of preterm delivery, but the impact of social mobility has not been studied before. PARTICIPANTS: The study uses national cohorts in which women act as their own controls. Subjects were identified by means of registries: 10,455 women who gave birth to a preterm child and had a subsequent live birth between 1980 and 1992 and 9849 women who gave birth to a child after 37 completed weeks of gestation and had a subsequent live born child in the same time period formed the cohorts. METHODS: The risk of having a premature infant in the subsequent pregnancy was analysed in each cohort as a function of changes in male partner, residency, occupation, and social status between the two pregnancies. RESULTS: There was a strong tendency to repeat a preterm delivery (18% v 6% in the general population). Social decline was associated with a moderate increase in the recurrence risk (OR: 1.22; 95% CI: 1.02, 1.47). In the reference cohort the risk of preterm delivery associated with changing from a rural to an urban municipality was 2.03 (95% CI: 1.14, 3.64). CONCLUSIONS: Social decline and moving to an urban municipality may be associated with preterm delivery.     

湖北省HIV感染孕产妇早产现状与影响因素分析

目的 了解湖北省HIV感染孕产妇早产的流行情况,探讨其相关影响因素,为制定预防HIV感染孕产妇早产的策略和措施提供参考依据。方法 收集2004—2020年全国预防艾滋病母婴传播管理信息系统中湖北地区报告的已分娩的HIV感染孕产妇相关流行病学调查资料,采用单因素χ2检验和Poisson回归模型,分析HIV感染孕产妇早产情况及其影响因素。结果 湖北省HIV感染孕产妇早产率为10.70%（66/617）,呈逐年上升趋势（χ2趋势 = 4.942,P = 0.026）,不同地区间HIV感染孕产妇早产率的差异无统计学意义。Poisson回归模型分析结果显示,年龄（35～49）岁（RR = 2.080,95%CI:1.177～3.678）、注射毒品感染HIV（RR = 2.899,95%CI:1.540～5.456）、孕期末次病毒载量≥1 000拷贝/mm3（RR = 4.567,95%CI:1.984～10.516）、胎膜早破（RR = 2.395,95%CI:1.063～5.393）、妊娠合并肝病（RR = 2.268,95%CI:1.154～4.455）和妊娠期高血压（RR = 3.540,95%CI:2.063～6.075）是影响HIV感染孕产妇早产的危险因素（P＜0.05）,不含蛋白酶抑制剂（PI）的三联用药方式（RR = 0.461,95%CI:0.231～0.917）是影响HIV感染孕产妇早产的保护性因素（P＜0.05）。结论 对于HIV感染孕产妇而言,加强围产期保健,采用不含PI的三联抗病毒治疗方案,控制孕期病毒载量水平、妊娠高血压疾病、妊娠合并肝病、胎膜早破等风险因素是降低其早产发生率的重要措施。     

Preterm birth subtypes among blacks and whites.

The differences in preterm birth between blacks and whites are poorly understood. Our study examined subtypes of moderately preterm delivery (34-36 completed weeks of gestation) and very preterm delivery (20-33 weeks) in blacks and whites using North Carolina birth certificate data for 1988-1989. We divided the causes of preterm birth into three categories: preterm premature rupture of the membranes, indication of pregnancy complication, and idiopathic preterm deliveries. The overall prevalence of preterm birth was 8.0% and 16.7% for whites and blacks, respectively. The entire gestational age distribution of blacks was shifted to earlier ages relative to whites. More highly educated blacks still had higher risks of moderately and very preterm deliveries than less educated whites. Multivariate analysis, controlling for other factors, showed that blacks had 3.3, 2.5, and 3.5 times the risk of whites to have preterm premature rupture of the membranes, complication-related, and idiopathic delivery, respectively, among very preterm births, and 1.6, 1.9, and 2.0 times the risk of whites for moderately preterm births of the same three types.     

History of fetal loss and other adverse pregnancy outcomes in relation to subsequent risk of preterm delivery

Objective: To evaluate the association between maternal reproductive history and preterm delivery. Methods: The 312 preterm delivery cases, studied in aggregate, and in subgroups (spontaneous preterm labor, preterm premature rupture of membranes, medically induced preterm delivery, moderate preterm delivery [gestational age at delivery 34–36 weeks], and very preterm delivery [gestational age at delivery <34 weeks]), were compared with 424 randomly selected women who delivered at term. Maternal medical records provided information on maternal reproductive history, pregnancy outcome, as well as sociodemographic characteristics. Using multivariate logistic regression, we derived maximum likelihood estimates of adjusted odds ratios (OR) and 95% confidence intervals (CI). Results: A history of 2+ miscarriages was ( OR = 2.2; 95% CI 1.2–3.9), but a history of 2+ prior induced abortions (OR = 1.2; 95% CI 0.7–2.0) was not, associated with preterm delivery in the index pregnancy. Analyses of preterm delivery subgroups indicated that a history of 2+ miscarriages was associated with an increasedrisk of spontaneous preterm labor (OR = 2.6; 95% CI 1.2–2.8), preterm premature rupture of membrane (OR = 1.8; 95% 0.7–4.4), and medically induced preterm delivery (OR = 1.9; 95% CI 0.8–4.2), though only the former approached statistical significance. Excess risk of preterm delivery was associated with maternal prior history of delivering a stillborn infant (OR = 10.7), a prior history of delivering a newborn that later died during the neonatal period (OR = 3.2), and a prior history of having a pregnancy complicated by spontaneous preterm delivery (OR = 6.0). Generally these associations were evident for each subgroup of preterm delivery, though inferences were often hindered by our relatively small sample size. Conclusions: These results support the hypothesis that maternal adverse reproductive history is associated with an increased risk of preterm labor and delivery.     

Race, cardiovascular reactivity, and preterm delivery among active-duty military women

BACKGROUND: Rates of preterm delivery in the United States are higher in black women compared with whites. In this study, we examined cardiovascular reactivity and risk of preterm delivery among black and white military women. METHODS: We recruited a total of 500 black and white active-duty military women from the prenatal clinic at a large military installation, interviewing them early in pregnancy and again at 28 weeks of gestation. A subgroup of women underwent a computerized stress test to determine cardiovascular reactivity assessed as increases in heart rate and blood pressure compared with measurements taken before the stress test. RESULTS: Despite a relatively low overall risk of preterm delivery (8.2%), we found the same 2-fold racial disparity reported in other populations (hazard ratio for preterm delivery in black women vs whites = 2.30; 95% confidence interval = 1.24-4.27). The disparity is present in all military ranks and is largest for medically indicated preterm deliveries. Among the 313 subjects who participated in the computerized stress testing, blacks exhibited more cardiac reactivity than whites. In black subjects only, a 1-mm increase in diastolic blood pressure reactivity was associated with 1.1 a day earlier delivery (-0.17 weeks). A similar trend was seen with heart rate. CONCLUSIONS: Autonomic dysfunction after exposure to stressors may play a role in the timing of delivery among black women.     

A time-series analysis of air pollution and preterm birth in Pennsylvania, 1997-2001

Preterm delivery can lead to serious infant health outcomes, including death and lifelong disability. Small increases in preterm delivery risk in relation to spatial gradients of air pollution have been reported, but previous studies may have controlled inadequately for individual factors. Using a time-series analysis, which eliminates potential confounding by individual risk factors that do not change over short periods of time, we investigated the effect of ambient outdoor particulate matter with diameter < or = 10 microm (PM10) and sulfur dioxide on risk for preterm delivery. Daily counts of preterm births were obtained from birth records in four Pennsylvania counties from 1997 through 2001. We observed increased risk for preterm delivery with exposure to average PM10 and SO2 in the 6 weeks before birth [respectively, relative risk (RR) = 1.07; 95% confidence interval (CI), 0.98-1.18 per 50 microg/m3 increase; RR = 1.15; 95% CI, 1.00-1. 32 per 15 ppb increase], adjusting for long-term preterm delivery trends, co-pollutants, and offsetting by the number of gestations at risk. We also examined lags up to 7 days before the birth and found an acute effect of exposure to PM10 2 days and 5 days before birth (respectively, RR = 1.10; 95% CI, 1.00-1.21; RR = 1.07; 95% CI, 0.98-1.18) and SO2 3 days before birth (RR = 1.07; 95% CI, 0.99-1.15), adjusting for covariates, including temperature, dew point temperature, and day of the week. The results from this time-series analysis, which provides evidence of an increase in preterm birth risk with exposure to PM10 and SO2, are consistent with prior investigations of spatial contrasts.     

Effect of marijuana use in pregnancy on fetal growth

In a prospective study of 3,857 pregnancies ending in singleton live births at Yale-New Haven Hospital, New Haven, Connecticut, in 1980-1982, 9.5% of mothers reported using marijuana (4.1% occasionally and 5.4% at least 2-3 times monthly). Among white women, regular use was associated with an increased risk of delivering a low birth weight (less than 2,500 gm) infant (odds ratio (OR) = 2.6, 95% confidence interval (CI) = 1.1-6.2) and small for gestational age infant (OR = 2.3, 95% CI = 1.3-4.1) after adjustment for other risk factors. Nonwhite marijuana users were not at further increased risk for delivering a low birth weight or small gestational age infant beyond the elevated rates of these conditions already experienced by nonwhites in general. Marijuana use was also related to preterm delivery (gestational age less than 37 weeks from last menstrual period) in white women (OR = 1.9, 95% CI = 1.0-3.9) but not nonwhite women. Occasional use was unrelated to the risk of low birth weight, small for gestational age, or preterm delivery.     

Occupational working conditions as risk factors for preterm birth in Benin, West Africa

BACKGROUND: Although many studies from developed countries have established a relationship between various occupational working conditions during pregnancy and preterm birth, there is little data available in developing countries where both maternal physical labor during pregnancy and preterm birth are common. The aim of this study was to examine the association between difficult occupational working conditions of pregnant women and premature births in the Republic of Benin in West Africa. METHOD: The case-control study included 99 women with preterm babies and 104 women with full-term babies. The participants were residents of the Republic of Benin who delivered between May 1, 2000 and April 30, 2002. Preterm delivery was defined as delivery prior to 37 completed weeks of gestation. The study sample was selected randomly from birth records. Data were collected both reviewing birth records and conducting semi-structured personal interviews with mothers. Logistic regression models were adjusted for mother's age, mother's education, health problems during pregnancy, and twin birth. RESULTS: Although working state of mother during pregnancy did not increase the risk for preterm delivery, carrying heavy loads more than 5 days per week was significantly associated with having a preterm baby (adjusted OR: 5.0; 95% CI: 1.38-18.8; P=0.018). Carrying heavy loads and having worked a lot more than 5 days per week was also significantly associated with preterm birth (adjusted OR: 6.88; 95% CI: 1.45-32.2; P=0.015). CONCLUSION: Reducing heavy loads carrying during pregnancy may also prevent preterm delivery in developing countries. Though replication of these data using a prospective design is needed, our results suggest that educating women about the risks associated with heavy labor during pregnancy is indicated.     

Weight loss during pregnancy is associated with adverse pregnancy outcomes among HIV-1 infected women

In a prospective study of 1002 pregnant, HIV-1 infected Tanzanian women, we examined the incidence of fetal death, preterm delivery, low birth weight (LBW), and small for gestational age (SGA) births in relation to maternal anthropometry at the first prenatal visit, weight loss, and low weight gain during pregnancy. Anthropometric measurements were obtained monthly during the 2nd and 3rd trimesters. Low maternal height and weight at the first visit were significantly related to lower mean birth weight and increased risk of SGA, but not to preterm delivery. Maternal stature < 150 cm was significantly related to fetal death. Weight loss during pregnancy, defined as a negative slope of the regression of weight measurements on the week of gestation, occurred in 10% of the women. It was related to increased relative risk (RR) of fetal death (RR = 1.83, 95% CI = 0.93, 3.57), preterm delivery (RR = 1.85, 95% CI = 1.40, 2.44), and LBW (RR = 2.85, 95% CI = 1.69, 4.79) after adjusting for multivitamin supplementation, height, primiparity, baseline weight, malaria, CD4 cell count, HIV disease stage, and intestinal parasitoses. The significant association with fetal death was stronger for weight loss during the 2nd trimester, whereas increased risks of preterm delivery and LBW were higher for weight loss during the 3rd. Similar but weaker associations were found with low weight gain during pregnancy (slope < 25th percentile). We conclude that poor anthropometric status at the first prenatal visit and weight loss during pregnancy among HIV-1 infected women are strong risk factors for adverse pregnancy outcomes.     

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...     

Familial patterns of preterm delivery: maternal and fetal contributions

Women who deliver preterm (<37 completed weeks' gestation) are at high risk for recurrence. This has prompted exploration of candidate genes (both maternal and fetal) associated with preterm delivery. Epidemiologists can use recurrence patterns of preterm delivery across generations to assess the relative contributions of maternal and fetal genes. The authors used data from the Medical Birth Registry of Norway (1967-2004) to identify 191,282 mothers and 127,830 fathers who subsequently had at least one singleton offspring. The authors stratified parents according to whether or not they had been born preterm and calculated the risk of preterm delivery among their firstborn. Mothers born preterm had a relative risk for preterm delivery of 1.54 (95% confidence interval (CI): 1.42, 1.67). This association was weaker for fathers born preterm (relative risk (RR) = 1.12, 95% CI: 1.01, 1.25). Among early preterm births (<35 weeks), the effect became stronger for mothers (RR = 1.85, 95% CI: 1.52, 2.27) and weaker for fathers (RR = 1.06, 95% CI: 0.77, 1.44). These data suggest that paternal genes have little, if any, effect on preterm delivery risk. This argues against major contributions of fetal genes inherited from either parent. The increased risk of preterm delivery among mothers born preterm is consistent with heritable maternal phenotypes that confer a propensity to deliver preterm.