Pregnancy Intendedness,Maternal Psychosocial Factors and Preterm Birth

Objectives: This study examined associations between reported pregnancy intendedness and several maternal psychosocial factors in relation to preterm birth (<37 weeks' completed gestation). Methods: Women were recruited into a prospective cohort study between the 24th and 29th weeks of pregnancy in central North Carolina from 1996 to 2000. Prior to delivery, participants responded to questions about pregnancy intendedness, life events impacts, depressive symptoms, and coping style. Results: Women who reported not intending their pregnancy had increased odds of reporting low, medium and high levels of perceived stress during pregnancy (OR = 1.4 [95% CI: 1.1, 1.9], OR = 2.2 [95% CI: 1.7, 2.8], and OR = 3.4 [95% CI: 2.6, 4.5], respectively, relative to very low), medium and high levels of depressive symptoms (OR = 2.2 [95% CI: 1.8, 2.9] and OR = 3.1 [95% CI: 2.4, 3.9], respectively), and medium and high levels of several coping styles. Reporting not intending the pregnancy was not associated with increased risk of preterm birth (Risk Ratio [RR] = 1.0, 95% CI: 0.8, 1.1), but reporting the highest quartile of perceived stress (RR = 1.6, 95% CI: 1.1, 2.3) and the highest tertile of distancing coping style (compared with lowest quartile) was associated with preterm birth (RR = 1.4, 95% CI: 1.1, 1.9). Interactions between pregnancy intendedness and the psychosocial variables perceived stress, depression or coping style did not modify the psychosocial variable's associations with preterm birth. Conclusions: Pregnancy intendedness remains an important concept in the reproductive health literature integrally tied to indicators of maternal mental health, but not necessarily to pregnancy outcomes.     

Risk of Spontaneous Preterm Birth in Relation to Maternal Exposure to Intimate Partner Violence During Pregnancy in Peru

Intimate partner violence (IPV) is increasingly recognized as an important cause of maternal and perinatal morbidity. We assessed the relation between IPV and risk of spontaneous preterm birth (PTB) among Peruvian women. The study was conducted among 479 pregnant women who delivered a preterm singleton infant (<37 weeks gestation) and 480 controls (≥37 weeks gestation). Participants’ exposure to physical and emotional violence during pregnancy was collected during in-person interviews conducted after delivery and while patients were in hospital. Odds ratios (aOR) and 95 % confidence intervals (CI) were estimated from logistic regression models. The prevalence of any IPV during pregnancy was 52.2 % among cases and 34.6 % among controls. Compared with those reporting no exposure to IPV during pregnancy, women reporting any exposure had a 2.1-fold increased risk of PTB (95 % CI 1.59–2.68). The association was attenuated slightly after adjusting for maternal age, pre-pregnancy weight, and other covariates (OR = 1.99; 95 % CI 1.52–2.61). Emotional abuse in the absence of physical violence was associated with a 1.6-fold (95 % CI 1.21–2.15) increased risk of PTB. Emotional and physical abuse during pregnancy was associated with a 4.7-fold increased risk of PTB (95 % CI 2.74–7.92). Associations of similar directions and magnitudes were observed when PTB were sub-categorized according to clinical presentation or severity. IPV among pregnant women is common and is associated with an increased risk of PTB. Our findings and those of others support recent calls for coordinated global health efforts to prevent violence against women.     

Daytime Napping and Nighttime Sleep During Pregnancy and Preterm Birth in Iran

ObjectivesThis study investigated the relationship between sleep quality during pregnancy and preterm birth.MethodsThis longitudinal study was conducted between August 2018 and May 2019. The participants were 150 pregnant women who had been referred to 7 healthcare centers in the city of Qazvin, Iran and met the inclusion criteria. The Petersburg Sleep Quality Index, the Epworth Sleepiness Scale, and 2 questions about daytime sleep status and a demographic questionnaire were administered at 14-18 weeks and 28-32 weeks of gestation. Data were analyzed using the Mann-Whitney test, the Fisher exact test, and univariate and multivariable logistic regression.ResultsIn the present study, poor sleep quality affected 84.7% of the participants at 14-18 weeks and 93.3% at 28-32 weeks of gestation. The final model for preterm birth prediction incorporated age and the Petersburg Sleep Quality Index score in the second and third trimesters. Preterm birth increased by 14% with each unit increase in age. With each unit increase in the Petersburg Sleep Quality Index score in the second and third trimesters, preterm birth increased by 42% and 28%, respectively, but the p-values of these factors were not significant.ConclusionsAlthough a significant percentage of pregnant women had poor sleep quality, no significant relationship was found between sleep quality during pregnancy and preterm birth.     

Maternal Employment During Pregnancy and Birth Outcomes: Evidence From Danish Siblings

I use Danish survey and administrative data to examine the impact of maternal employment during pregnancy on birth outcomes. As healthier mothers are more likely to work and health shocks to mothers may impact employment and birth outcomes, I combine two strategies: First, I control extensively for time‐varying factors that may correlate with employment and birth outcomes, such as pre‐pregnancy family income and maternal occupation, pregnancy‐related health shocks, maternal sick listing, and health behaviors (smoking and alcohol consumption). Second, to account for remaining time‐invariant heterogeneity between mothers, I compare outcomes of mothers’ consecutive children. Mothers who work during the first pregnancy trimester have a lower risk of preterm birth. I find no effect on the probability of having a baby of small size for gestational age. To rule out that health selection of mothers between pregnancies drives the results, I focus on mothers whose change in employment status is likely not to be driven by underlying health (mothers who are students in one of their pregnancies and mothers with closely spaced births). Given generous welfare benefits and strict workplace regulations in Denmark, my findings support a residual explanation, namely, that exclusion from employment may stress mothers in countries with high‐female employment rates. Copyright © 2014 John Wiley & Sons, Ltd.     

Teen Maternal Age and Very Preterm Birth of Twins

Background: As teen singleton pregnancy is associated with higher risks of adverse birth outcome, and twin pregnancy, regardless of maternal age, may result in poor outcome, teens pregnant with twins may represent a particularly vulnerable group. However, little has been documented regarding teen twin pregnancy outcome. Objective: To characterize the risk of very preterm birth among teens having twins. Design: Cross-sectional analysis of the US 1995–2000 Matched Multiple Birth Data Set. Methods: We calculated the risk of very preterm birth (<33 weeks' gestation) for teen and young adult mothers of twins (≤16 years, 17–18 years, 19–20 years), compared to 21–24 year olds, stratified by race/ethnicity. Adjusted odds ratios were estimated controlling for marital status and entry into prenatal care. Results: Odds of very preterm birth decreased significantly with increasing age. Odds ratios ranged from 2.07 (1.73,2.48) to 1.20 (1.11,1.29) according to maternal age for White teen mothers, from 1.76 (1.48,2.09) to 1.13 (1.03,1.24) for Black teen mothers, and from 2.19 (1.77,2.72) to 1.15 (1.02,1.31) for Hispanic teen mothers. Odds of very preterm birth among teen mothers of twins were about the same as those for teen mothers of singletons. Conclusions: Teens having twins have higher odds of very preterm birth than young adult mothers. However, the association between age and preterm birth was similar among teen mothers having twins as for those having singletons.     

Psychosocial Stress and Preterm Birth: The Impact of Parity and Race

Objectives Studies examining risk factors for preterm birth (PTB) such as psychosocial stress are often focused on women with a history of PTB; however, most preterm babies are born to women with no history of preterm birth. Our objective was to determine if the relationship between psychosocial stress and PTB is altered by parity. Non-Hispanic black (NHB) women have increased psychosocial stress and PTB; therefore, we further aimed to determine if race alters the relationship between psychosocial stress, parity, and PTB. Methods We performed a secondary analysis of the Healthy Pregnancy, Healthy Baby Study comparing pregnant women who were primiparous (first pregnancy), multiparous with history of preterm birth, or multiparous with history of term birth. Perceived stress, perceived racism, interpersonal support, John Henryism and self-efficacy were measured using validated instruments. Logistic regression was used to model the effect of psychosocial stress on PTB stratified by parity and race. Results The analysis entire cohort included 1606 subjects, 426 were primiparous, 268 had a history of presterm birth, and 912 had a history of term birth. In women with a history of term birth, higher self-efficacy was associated with lower odds of spontaneous PTB, and this association was amplified in NHB women. In women with a history of spontaneous PTB, John Henryism Active Coping was associated with lower odds of spontaneous PTB in the index pregnancy. Conclusions for Practice The relationship between psychosocial stress and PTB may be mediated by parity and race.     

Predicting Phenotype and Emerging Strains among Chlamydia trachomatis Infections

Chlamydia trachomatis is a global cause of blinding trachoma and sexually transmitted infections (STIs). We used comparative genomics of the family Chlamydiaceae to select conserved housekeeping genes for C. trachomatis multilocus sequencing, characterizing 19 reference and 68 clinical isolates from 6 continental/subcontinental regions. There were 44 sequence types (ST). Identical STs for STI isolates were recovered from different regions, whereas STs for trachoma isolates were restricted by continent. Twenty-nine of 52 alleles had nonuniform distributions of frequencies across regions (p<0.001). Phylogenetic analysis showed 3 disease clusters: invasive lymphogranuloma venereum strains, globally prevalent noninvasive STI strains (ompA genotypes D/Da, E, and F), and nonprevalent STI strains with a trachoma subcluster. Recombinant strains were observed among STI clusters. Single nucleotide polymorphisms (SNPs) were predictive of disease specificity. Multilocus and SNP typing can now be used to detect diverse and emerging C. trachomatis strains for epidemiologic and evolutionary studies of trachoma and STI populations worldwide.     

Relationship Between Common Mental Disorder Symptoms During Pregnancy and Preterm Birth Among Chinese Women in Wuhan

Objectives Few studies focus on the symptoms of common mental disorders during pregnancy (CMDP) and risk of preterm birth subtypes (PTB). The purpose of this study was to estimate the association between CMDP and PTB, and to examine whether or not the association between CMDP and PTB varies with the subtype of PTB in Chinese. Methods This population-based case control study, conducted in Wuhan, China, defined cases as every pregnant woman who had a PTB among all births in Wuhan, from June 10, 2011, to June 9, 2013. The same number of pregnant women who had term births was randomly selected as controls. The Electronic Perinatal Health Care Information System, a questionnaire designed for the study, provided data about the participants. Logistic regression analyses were used to model associations betweenCMDP and PTB, and to test associations between CMDP and two subtypes of PTB. Results The study recruited 8616 cases and an equal number of controls. We successfully collected maternal information on 6656 cases and controls for a response rate of 77.3 %. The incidence of PTB in Wuhan was 4.5 %. Spontaneous preterm births (SPTB) accounted for 60.1 %, and medically induced preterm births (IPTB) accounted for 39.9 % of preterm births. The prevalence rate of CMDP was 15.8 %. CMDP was slightly associated with PTB (crude OR 1.16, 95 % CI 1.01–1.32; adjusted OR 1.15, 95 % CI 1.00–1.32), further analyses showed CMDP was associated with IPTB (aOR 1.25, 95 % CI 1.04–1.50), but not with SPTB. Conclusion Our data suggest that CMDP is related to an increased risk of PTB, and that this association is primarily due to IPTB rather than SPTB.     

荧光定量聚合酶链反应对女性生殖道感染解脲脲支原体及沙眼衣原体检测分析

目的 了解女性生殖道感染者解脲脲支原体(Uu)和沙眼衣原体(Ct)的感染情况,为临床诊断与治疗提供试验依据.方法 对374例女性生殖道感染者按常规取宫颈或阴道分泌物,利用荧光定量聚合酶链反应(FQ-PCR)方法分别进行Uu和Ct检测.结果 374例生殖道感染女性中Uu感染率61.7%,Ct感染率6.6%,Uu和Ct混合感染率6.0%;将患者按年龄分为18～20、21～30、31～40、41～50、＞50岁5个组,其Uu和Ct检测阳性率分别为72.7%和50.0%、62.7%和5.6%、62.0%和5.4%、28.6%和0、0和0.结论 在女性生殖道感染常见病原体中Uu感染率明显高于Ct,而且Uu多以单独感染形式为主,Ct多以混合感染为主,两种病原体的感染率都随着年龄的递增有递减的趋势;对生殖道感染女性常规检测Uu和Ct,对指导临床治疗具有重要意义.     

大气污染对低出生体重和早产影响的Meta分析

目的 研究各主要大气污染物对低出生体重(LSW)和早产的影响.方法 通过计算机检索收集国内外1999-2009年公开发表的有关大气污染对不良妊娠结局影响的相关文献14篇,按照制定的纳入排除标准对文献进行筛选,利用Stata9.0的Meta模块对人选文献进行异质性检验和相应的效应值合并.采用Meta分析获得的合并OR值作为最终的合并效应值.结果 建立各主要污染物与低出生体重和早产的暴露.反应关系,其中PM10浓度每升高50μg/m3,所对应的低出生体重及早产发生的合并OR值分别为1.07(95%CI:1.024～1.119,P＜0.01)、1.217(95%CI:1.045～1.415,P＜0.05);SO2浓度每升高43λg/m3(15 ppb),所对应的低出生体重或早产发生的合并OR值分别为1.137(95%CI:1.047～1.235,P＜0.05)、1.163(95%CI:1.082～1.250,P＜0.01);NO2每升高21μg/m3(10 ppb),所对应的低出生体重发生的合并OR值为1.03(95%CI:1.008～1.054,P＜0.01);CO每升高1.25 mg/m3(1 ppm),所对应的低出生体重发生的合并OR值为1.066(95%C1:1.016～1.117,P＜0.01);NO2以及CO对早产影响的合并效应值无统计学意义(P＞0.05).结论 本研究综合定量分析的结果 表明,大气污染能够增加低出生体重和早产发生的危险,妊娠期妇女有必要采取有效的措施减少大气污染的暴露.     

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.

     

Impact of State Cigarette Taxes on Disparities in Maternal Smoking During Pregnancy

Objectives. We evaluated the impact of state tobacco control policies on disparities in maternal smoking during pregnancy.Methods. We analyzed 2000–2010 National Vital Statistics System natality files with 17 699 534 births from 28 states and the District of Columbia that used the 1989 revision of the birth certificate. We conducted differences-in-differences regression models to assess whether changes in cigarette taxes and smoke-free legislation were associated with changes in maternal smoking during pregnancy and number of cigarettes smoked. To evaluate disparities, we included interaction terms between maternal race/ethnicity, education, and cigarette taxes.Results. Although maternal smoking decreased from 11.6% to 8.9%, White and Black women without a high school degree had some of the highest rates of smoking (39.7% and 16.4%, respectively). These same women were the most responsive to cigarette tax increases, but not to smoke-free legislation. For every $1.00 cigarette tax increase, low-educated White and Black mothers decreased smoking by nearly 2 percentage points and smoked between 14 and 22 fewer cigarettes per month.Conclusions. State cigarette taxes may be an effective population-level intervention to decrease racial/ethnic and socioeconomic disparities in maternal smoking during pregnancy.A substantial literature has demonstrated the success of cigarette taxes on decreasing adult smoking.1–3 State taxes in 2013 ranged from $0.17 in Missouri to $4.35 in New York,4 and 2010 smoking levels in women were at 17%.5 Low-income adults, a group with the highest levels of smoking,5 have been shown to be more sensitive to tax increases.2,6 Despite racial/ethnic differences in smoking rates,5 less is known about whether responsiveness to taxes also varies.7 Over the past decade, many US states have enacted smoke-free legislation in the workplace, restaurants, or both in addition to increasing cigarette taxes. Although the aim of smoke-free policies is to protect nonsmokers from secondhand smoke, for which they have been very effective,8,9 the evidence for their impact on smoking rates is limited.1,9,10Despite these achievements, a population that has received little attention is pregnant women. The detrimental effects of smoking on maternal and fetal health11 and other household members through secondhand smoke exposure are well known.12 Although pregnancy is often a time of positive behavioral change, as of 2008, 10% to 15% of women smoked during pregnancy.13–15 However, these overall estimates masked racial/ethnic and socioeconomic gradients, such that 16% of White, 9% to 10% of Black, and 2% to 4% of Hispanic mothers smoked during pregnancy,14,15 and women with 12 or less years of education were more than 3 times (19.4%–22.3%) as likely to smoke during pregnancy as women with more than 12 years of education (6.5%).15Previous studies using data from the 1990s have found that pregnant women are responsive to cigarette tax increases.16–19 Ringel and Evans16 used population-level data from 1989 through 1995 and found that every $1.00 increase in cigarette taxes decreased smoking by 6.6 percentage points but had no effect on the number of cigarettes smoked daily. Specifically, they found that women who were White, older, and higher educated were the most responsive to tax changes.16 However, smoking patterns, social norms, and the politics related to tobacco control have changed over the past 20 years. A more recent study by Adams et al.20 used state-representative data from 2000 through 2005 to assess both tax changes and smoke-free policies on quitting during pregnancy. They found that a $1.00 cigarette tax increase was associated with a 4.8 percentage point increase in quitting smoking, and a full smoking ban at private worksites increased quit rates by 5.1 percentage points.20 However, they were unable to examine racial/ethnic or socioeconomic differences because of small sample sizes.A substantial gap in the literature remains, specifically, the effect of recent tobacco control policies on smoking levels among those mothers at the highest risk for smoking. We were able to use population-level data to exploit the natural experiment created through cigarette tax increases and the enactment of smoke-free legislation across and within US states over the past decade. Our first aim was to examine disparities in maternal smoking during pregnancy across and within racial/ethnic groups and, second, to evaluate the impact of state tobacco control policies on disparities in maternal smoking.     

Temporal Changes in Socioeconomic Influences on Health: Maternal Education and Preterm Birth

Objectives. To consider how the relationships between social determinants and health indicators change over time, we assessed the time-varying influence of maternal education on risk of preterm birth (PTB) between 1989 and 2006.Methods. We used bivariate and multivariable Poisson regression models with robust variation estimates to examine (1) the association between maternal education and PTB risk by year; (2) the relationship between low maternal education and PTB, late PTB, and very PTB risk by year relative to 1989; and (3) the relationship between high maternal education and PTB, late PTB, and very PTB risk by year relative to 1989.Results. After adjustment, PTB risk increased among the most educated and did not change among the least educated women over time. Risk of PTB among the least educated relative to the most educated women decreased with time. Late PTB risk increased among both the most and the least educated groups but more among the most educated.Conclusions. Maternal education may be becoming less protective against PTB. The influence of the social determinants of health is dynamic, warranting revisions of our understanding of their roles over time.The association between lower socioeconomic position and poor health is among the most robust epidemiological relationships documented. The association between socioeconomic metrics such as education,1,2 household income,1,3 occupational status,1,4 and neighborhood deprivation5,6 and adverse health has been described in the context of mortality,7 cancer,8 cardiovascular disease,9,10 diabetes,11 obesity,12 mental health,2,5,13 and several other adverse health indicators.In their work on fundamental cause theory, Link and Phelan14 suggested that higher social status is always associated with better health simply because social status—through access to more knowledge, money, power, social connectedness, and prestige—affords access to resources that can optimize health even if these resources change over time. In that way, it is entirely plausible that the salutary resources associated with a particular social factor may change with time. For example, it is likely that the extent to which high education affords relatively better access to health information changes over time as health information infiltrates all levels of social status. This would result in differing temporal relationships between social factors and health indicators and would suggest that we need to consider and recognize that the links between social factors and health indicators likely change over time. In this way a dynamic, rather than a static, approach to the study of social determinants is indicated. However, with very few exceptions, there is scant literature that has considered how the relationship between social determinants and health indicators changes over time in this way.Of interest here is the association between maternal education and the risk of preterm birth (PTB), which has been well documented.15–18 PTB is defined as birth before 37 completed weeks of gestation or birth before 259 days since the first day of the mother’s last menstrual period.19 Although only 6% to 10% of all births are preterm in wealthy countries, preterm neonatal deaths account for more than two thirds of all neonatal deaths in this context.19 PTB is an important determinant of serious neonatal morbidity, moderate to severe childhood disability, and perinatal and neonatal mortality in wealthy countries.18,19Given the potential for changes in the relationships between social determinants and health indicators, we assessed how the association between maternal education and PTB changed over time to understand how secular changes in social factors may influence their roles as health determinants. We assessed the time-varying influence of maternal education on the risk of PTB from 1989 through 2006.     

Urinary Bisphenol A Levels during Pregnancy and Risk of Preterm Birth

Background

Preterm birth (PTB), a leading cause of infant mortality and morbidity, has a complex etiology with a multitude of interacting causes and risk factors. The role of environmental contaminants, particularly bisphenol A (BPA), is understudied with regard to PTB.

Objectives

In the present study we examined the relationship between longitudinally measured BPA exposure during gestation and PTB.

Methods

A nested case–control study was performed from women enrolled in a prospective birth cohort study at Brigham and Women’s Hospital in Boston, Massachusetts, during 2006–2008. Urine samples were analyzed for BPA concentrations at a minimum of three time points during pregnancy on 130 cases of PTB and 352 randomly assigned controls. Clinical classifications of PTB were defined as “spontaneous,” which was preceded by spontaneous preterm labor or preterm premature rupture of membranes, or “placental,” which was preceded by preeclampsia or intrauterine growth restriction.

Results

Geometric mean concentrations of BPA did not differ significantly between cases and controls. In adjusted models, urinary BPA averaged across pregnancy was not significantly associated with PTB. When examining clinical classifications of PTB, urinary BPA late in pregnancy was significantly associated with increased odds of delivering a spontaneous PTB. After stratification on infant’s sex, averaged BPA exposure during pregnancy was associated with significantly increased odds of being delivered preterm among females, but not males.

Conclusions

These results provide little evidence of a relationship between BPA and prematurity, though further research may be warranted given the generalizability of participant recruitment from a tertiary teaching hospital, limited sample size, and significant associations among females and within the clinical subcategories of PTB.

Citation

Cantonwine DE, Ferguson KK, Mukherjee B, McElrath TF, Meeker JD. 2015. Urinary bisphenol A levels during pregnancy and risk of preterm birth. Environ Health Perspect 123:895–901; http://dx.doi.org/10.1289/ehp.1408126     

Effects of Dietary Patterns during Pregnancy on Preterm Birth: A Birth Cohort Study in Shanghai

The objective of this study was to analyse representative dietary patterns during pregnancy in Shanghai and explore the effects of dietary patterns during pregnancy on preterm birth. Data were derived from the ‘Iodine Status in Pregnancy and Offspring Health Cohort’ (ISPOHC) study. Multistage, stratified random sampling was used to select survey participants from 16 districts in Shanghai, which were divided into five sampling areas; 40–70 pregnant women were selected from each area. A total of 4361 pregnant women and their offspring were involved in the study. The male-to-female ratio of the babies was 1.04:1, and the incidence of single preterm birth was 4.2%. Three dietary patterns were extracted by factor analysis: a ‘Vegetarian Pattern’, an ‘Animal Food Pattern’ (AFP), and a ‘Dairy and Egg Pattern’. These patterns explained 40.513% of the variance in dietary intake. Binary logistic regression, which was used to analyse the association between birth outcomes and scores measuring maternal dietary patterns, found only the AFP was a significant risk factor for preterm birth. Higher AFP scores were positively associated with preterm birth (Q2 vs. Q1 OR = 1.487, 95% CI: 1.002–2.207; Q3 vs. Q1 OR = 1.885, 95% CI: 1.291–2.754). After adjusting for other potential contributors, a higher AFP score was still a significant risk factor for preterm birth (Q2 vs. Q1 OR = 1.470, 95% CI: 0.990–2.183; Q3 vs. Q1 OR = 1.899, 95% CI: 1.299–2.776). The incidence of preterm birth was 4.2%. A higher score of AFP was significantly associated with a higher risk of preterm birth. The animal food intake of pregnant women should be reasonably consumed during pregnancy.