Socio-economic factors associated with preterm delivery in Greece: a population-based study

Summary. A total population sample of singleton births to mothers with certain last menstrual period dates was identified from the Greek National Perinatal Survey of April 1983. Two groups were considered (3116 primigravidae and 6524 multigravidae) with preterm rates of 5.9% and 8.4% respectively. Of all 17 factors considered, primigravidae showed unadjusted significant associations between preterm delivery and marital status, region of mother's residence, maternal occupation, maternal education and paternal education level. Multigravidae preterm deliveries were associated with marital status, mother's age at marriage, father's age at marriage, mother's age at delivery, mother's education, father's education and maternal smoking at the end of the pregnancy. Logistic regression was used to identify the socio-economic and demographic characteristics independently associated with preterm delivery. For primigravidae, the only significant factors were maternal marital status and region of the country. For multigravidae, significant factors were maternal age at delivery, marital status and smoking habit at the end of pregnancy.     

Sociodemographic determinants of low birthweight in Greece: a population study

A total population sample of 10 654 singleton births from the Greek National Perinatal Survey of April 1983 was analysed to identify factors independently associated with low birthweight (LBW). The sample was divided into two groups according to the gravidity of the mothers (3368 primigravidae and 7286 multigravidae). Data examined included regional characteristics, marital status, age at and duration of marriage, parental ages at delivery, crowding in the home, insurance status, parental occupational classification and parental education levels. Logistic regression was used to define the socio-economic and demographic characteristics independently associated with the delivery of an LBW singleton baby. Significantly different LBW rates were found among the two groups: 4.3% in the primigravidae and 5.2% for multigravidae. For primigravidae significant associations were found with marital status, maternal occupation and father's education, while for multigravidae significant features were mother's education and place (region) of residence. The study showed little to assist in devising strategies of primary prevention of LBW in Greece.     

Delayed antenatal care: does it effect pregnancy outcome?

Information on 13,127 mothers who were certain of the date of their last menstrual period (LMP) and who delivered in one week of April 1970, was analysed to assess whether delayed attendance for antenatal care (defined as not attending prior to 28 weeks of gestation) was associated with adverse outcome of pregnancy. Background factors that had been found to be predictive of delayed attendance were as follows: region of residence, region of birth of the child's father, marital status and contraceptive use in the 18 months prior to conception for primigravidae and the same four variables together with parity, maternal age and interpregnancy interval for multigravidae. Both before and after these factors had been taken into account, there was no evidence of any association between delay in attendance for care and severe pre-eclampsia, perinatal mortality, pre-term delivery and birthweight, although after adjustment for the background factors the length of gestation in delayed attenders was, on average, 2 days longer.     

Antenatal care received and its association with preterm birth in Greece

A total population sample of singleton births to mothers with certain dates of last menstrual period (LMP) was identified from the Greek National Perinatal Survey of April 1983. Two groups of mothers were considered separately, 3116 primigravidae and 6524 multigravidae, with preterm birth rates of 5.9% and 8.4% respectively. Of all the antenatal care factors tested, primigravidae showed significant associations (unadjusted) with haematocrit level and with drugs taken during pregnancy. The logistic regression analysis which followed showed that the only factor independently associated with preterm delivery for that group of mothers was drugs taken during this period: women taking no drugs (including vitamins and iron) had the highest risk of preterm delivery. In contrast, multigravidae showed significant unadjusted associations with a great variety of parameters of antenatal care. Nevertheless, in the logistic regression analysis only three proved to have independent significant associations: drugs taken during pregnancy (reduced risk among mothers taking vitamins and iron), hospital admission during pregnancy (mainly for cervical cerclage) and the pattern of antenatal care during the first two trimesters (those attending the recommended number of times having least risk).     

Teenage smoking and antecedent parentalcharacteristics: A prospective study

The smoking habits of 1445 white adolescents aged 15 to 17 years were examined in relation to 16 characteristics of the family prevailing at the time the mother was pregnant with the child. Five characteristics were independently associated with teenage smoking, either for boys or girls or both: parental smoking, mother's education and age, father's education and occupation.Multiple regression showed that father's occupation was redundant for both boys andgirls, and that mother's education was redundant for boys' smoking. Parental smoking, father's education and mother's age each had predictive power for boys' smoking. For the girls, mother's education also had predictive power. In general, the major family characteristics associated at birth with later teenage smoking are parental smoking habits and socioeconomic status. The sex differences between associations of family characteristics and teenage smoking suggest that the like-sexed parents' smoking and education have the greater effect on teenage smoking, particularly for the boys. For girls, present smoking status of mother was of more importance than mother's smoking status at birth if the mother had given up smoking.     

Causal pathways to infant mortality: linking social variables to infant mortality through intermediate variables

Using a conceptual model that integrates social and biomedical models of causation, this paper delineates the pathways through which social factors ultimately influence infant mortality in the African-American community. Two social factors, maternal education and marital status, are shown to influence the risk of infant death through the following intermediate variables: bio-demographic (maternal age, birth order, birth interval and outcome of last pregnancy), health care (prenatal care utilization) and proximate infant health status at birth (preterm delivery and low birth weight). While the impact of maternal education is largely explained by the intermediate variables, marital status remains a significant, albeit a weak, predictor net of all other variables.     

Social determinants of birthweight and length of gestation in Estonia during the transition to democracy

BACKGROUND: To investigate social variation in birthweight and length of gestation in Estonia in the period of transition to a democracy and market economy. METHODS: All live births resulting from singleton pregnancies reported to the Estonian Medical Birth Registry in 1992-1997 (n = 84, 629) were studied with respect to social variation in birthweight and preterm delivery (<37 weeks gestation). The results were adjusted for maternal age, parity, education, nationality, marital status, smoking in pregnancy, sex of the infant (and gestational age). RESULTS: Between 1992 and 1997, mean birthweight increased from 3,465g to 3,497g (P < 0.001) and the preterm rate fell from 5.8% to 5.1% (P = 0.001). Maternal education, marital status and nationality were all independently related to the mean birthweight and the risk of preterm birth. The mean difference in birthweight between children of mothers with basic and university education was 87 g (95% CI : 74-100). Children born to mothers of non-Estonian compared to Estonian nationality were on average 77 g lighter (95% CI: 70-84). While the effect of nationality and marital status on birthweight was relatively stable during the study period, differences in birth outcome by maternal education became stronger. CONCLUSIONS: The mean birthweight increased and the preterm rate decreased in Estonia as a whole during the transition. However, the improvements were not shared equally by all social groups. An increase in variation in birthweight by maternal education was particularly notable.     

Maternal smoking habits and cognitive development of children at age 4 years in a population-based birth cohort

BACKGROUND: Active maternal smoking during pregnancy has been associated with a higher risk of behavioural disorders in children, but a few cohort studies measuring smoking data prospectively have studied its specific effects on the cognitive abilities of pre-schoolers. METHOD: A birth cohort was set up in Menorca Island in 1997 within the Asthma Multicenter Infants Cohort Study. A total of 420 (87% of those eligible) children had complete data for final analyses at age 4 years. Interviewer-administered questionnaires were completed by mothers during the third trimester of pregnancy and then every year up to age 4 years of their child. A standardized version of the McCarthy Scales of Children's Abilities (MCSA) was used to evaluate the child's motor and cognitive capabilities. Multivariable regressions were used with MCSA's assessed outcomes adjusting for: home location, maternal alcohol consumption, mother's social class and level of education during pregnancy, parity, marital status, father's education level, child's gender, birth weight and height, breastfeeding duration, passive smoking, school season, age during test administration and evaluator (psychologist). RESULTS: A high global consistency in maternal smoking habits was found (total agreement = 88.7%). Maternal social class and education level were inversely associated with maternal smoking behaviour. Maternal smoking during pregnancy (in cig./day) was associated with a decrease (in points) of children's global cognitive score [beta = -0.60, (95% CI: -1.10; -0.09)]; as well as global cognitive sub-areas like verbal score [beta = -0.59, (95% CI: -1.11; -0.07)]; quantitative score [beta = -0.57, (95% CI: -1.08; -0.06)]; executive function score [beta = -0.71, (95% CI: -1.23; -0.20)]; and working memory score [beta = -0.46, (95% CI: -0.92; -0.01)]. CONCLUSION: Our findings suggest an association with maternal smoking during pregnancy and lowered cognitive development in children at age 4 years.     

Socioeconomic and work related determinants of pregnancy outcome in southern Thailand

STUDY OBJECTIVE: To examine the effect of socioeconomic status on pregnancy outcome in an urbanised area in a rapidly developing country. METHODS: A cohort of 1797 pregnant women who attended antenatal care clinics at the two 700 bed hospitals in Hatyai city was recruited from September 1994 to November 1995. The pregnant women were followed up from the 17th week of gestation until delivery. The socioeconomic indicators selected were family socioeconomic status, maternal education, maternal occupation, family income and work exposure characteristics based upon Karasek's job content questionnaires. Pregnancy outcomes were birth weight, low birth weight, small for gestational age and preterm delivery. MAIN RESULTS: Mean birth weight correlated with socioeconomic status and income but after adjustment for parity, maternal age and height, weight at delivery day, baby sex, obstetrical complications and antenatal care utilisation, only family income remained correlated with birth weight. No association with any socioeconomic status indicators was found when using dichotomous outcome (low birth weight, small for gestational age or preterm delivery). Only high psychological job demand was associated with small for gestational age. Confounder adjustment indicated that the observed social status differences in pregnancy outcomes were mainly attributable to mother's characteristics and antenatal service use. CONCLUSIONS: Socioeconomic indicators alone were not associated with reduced fetal growth or preterm delivery in this study, which recruited mainly lower or middle class women. Karasek's psychological job demand was only weakly correlated with small for gestational age infant.     

Can we explain why Brazilian babies are becoming lighter?

BACKGROUND: We tried to explain why a marked decrease in birthweight of 122 g occurred over a 15-year period in Ribeir?o Preto, Brazil. METHODS: Factors reflecting biological, social, and health care characteristics (infant gender, parity, maternal age, marital status, type of hospital, maternal smoking, preterm birth, small for gestational age [SGA], and prenatal care) were assessed on 6711 newborns in 1978/1979 and 2838 in 1994 using multiple linear regressions. RESULTS: The birthweight distribution shifted to the left and the residual distribution of small preterm babies increased from 1.9% to 3.4%. Only marital status and preterm delivery would have decreased the difference in birthweight over time, explaining for each of them around 30 g of the 122 g. Increasing levels of attendance at antenatal care over time might have decreased the birthweight difference by 40 g. Maternal age and SGA explained little of the decreasing trend. Reductions in maternal smoking would have increased mean birthweight slightly. In stratified analysis the downward trend was more marked among mothers with high education (-202 g) and those delivered by caesarean section (-194 g). After adjusting for all those significant variables mean birthweight was still 74 g (95% CI: -97, -50 g) lower in 1994 than in 1978/1979. CONCLUSION: The trend could be explained in part by factors related to marital status that might reflect dysfunctional families in the Brazilian context and the preterm increase that might be associated with advances in medical technology. The high attendance at antenatal clinics or factors associated with it might have prevented a further decrease in birthweight. Our results may be compatible with the high economic development of Ribeir?o Preto within Brazil, together with factors associated with its unfavourable lifestyle.     

Ethnic differences in preterm and very preterm delivery.

Ethnic differences in preterm (less than 37 weeks) and very preterm (less than 33 weeks) delivery were evaluated in a prospective cohort of 28,330 women. Blacks had the highest rate of preterm and very preterm delivery, followed by Mexican-Americans, Asians, and Whites. Adjustment for maternal age, education, marital status, employment, parity, number of previous spontaneous or induced abortions, smoking and drinking during pregnancy, infant sex, and gestational age at initiation of prenatal care resulted in the following odds ratios for preterm delivery: 1.79 (1.55-2.08) for Blacks, 1.40 (1.19-1.63) for Mexican-Americans, 1.40 (1.16-1.69) for Asians, and 1.00 for Whites. The corresponding odds ratios for very preterm delivery were 2.35 (1.72-3.22) for Blacks, 1.31 (0.88-1.94) for Mexican-Americans, 1.10 (0.67-1.83) for Asians, and 1.00 for Whites. Exclusion of cases of premature rupture of membranes, placenta previa, and abruptio placenta did not explain the large ethnic differences. Although Whites and Mexican-Americans had similar birthweight distributions, Mexican-Americans had an increased risk for preterm delivery. Fifty-five per cent of low birthweight babies in Kaiser were preterm and this fraction did not vary substantially by ethnic group.     

Linking birth records to hospital admission records enhances the identification of women who smoke during pregnancy

Objective : Birth records and hospital admission records are valuable for research on maternal smoking, but individually are known to under‐estimate smokers. This study investigated the extent to which combining data from these records enhances the identification of pregnant smokers, and whether this affects research findings such as estimates of maternal smoking prevalence and risk of adverse pregnancy outcomes associated with smoking. Methods : A total of 846,039 birth records in New South Wales, Australia, (2001–2010) were linked to hospital admission records (delivery and antenatal). Algorithm 1 combined data from birth and delivery admission records, whereas algorithm 2 combined data from birth record, delivery and antenatal admission records. Associations between smoking and placental abruption, preterm birth, stillbirth, and low birthweight were assessed using multivariable logistic regression. Results : Algorithm 1 identified 127,612 smokers (smoking prevalence 15.1%), which was a 9.6% and 54.6% increase over the unenhanced identification from birth records alone (prevalence 13.8%), and delivery admission records alone (prevalence 9.8%), respectively. Algorithm 2 identified a further 2,408 smokers from antenatal admission records. The enhancement varied by maternal socio‐demographic characteristics (age, marital status, country of birth, socioeconomic status); obstetric factors (multi‐fetal pregnancy, diabetes, hypertension); and maternity hospital. Enhanced and unenhanced identification methods yielded similar odds ratios for placental abruption, preterm birth, stillbirth and low birthweight. Conclusions : Use of linked data improved the identification of pregnant smokers. Studies relying on a single data source should adjust for the under‐ascertainment of smokers among certain obstetric populations.     

Employment status of pregnant women in central Poland and the risk of preterm delivery and small-for-gestational-age infants

BACKGROUND: Unemployment is one of the consequences of the ongoing transformation of the Polish economy. The main objective of the present study was to investigate the relationship between women's employment status and preterm delivery (PD) and/or small-for-gestational-age (SGA) infants, in Central Poland during the socio-economic transition. METHODS: The study population comprised 8% random sample of 2,080 women from the Lodz macro region who gave birth to a child during a one-year period (1996-1997). Based on the employment status, three groups were distinguished: the employed (n = 1238), the unemployed (n = 128)--women who lost their job before pregnancy (at least 12 months prior to delivery) and were actively seeking employment, and the housewives (n = 714). Women with chronic medical problems diagnosed before pregnancy were excluded from the study. RESULTS: The rates of preterm delivery were found to be 6.3%, 11.7% and 4.9%, respectively for the employed, unemployed, and housewives. After adjustment for age, marital status, education, maternal height, smoking, own apartment, presence of cervical insufficiency and uterine irritability, an excess risk of PD was observed among the unemployed women (OR = 1.92, 95% CI: 1.01-3.64). Unemployment was associated, though not significantly, with higher rates of SGA births. CONCLUSION: In Central Poland, the unemployed pregnant women are characterised by an excess risk of preterm delivery. The impact of unemployment on the community's health, which seems to be underestimated, should be given more consideration in the national and local policies for public health.     

Increased risk of preterm delivery in areas with cancer mortality problems from petrochemical complexes

The petrochemical and petroleum industries are the main sources of industrial air pollution in Taiwan. Data in this study concern outdoor air pollution and the health of individuals living in communities in close proximity to petrochemical industrial complexes. The prevalence of delivery of preterm birth infants was significantly higher in mothers living near petrochemical industrial complexes than in control mothers living elsewhere in Taiwan. After controlling for several possible confounders (including maternal age, season, marital status, maternal education, and infant sex), the adjusted odds ratio was 1.18 (95% CI=1.04-1.34) for delivery of preterm infants in the petrochemically polluted region. The data provide further support for the hypothesis that air pollution can affect the outcome of pregnancy.     

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。     

Does alcohol increase the risk of preterm delivery?

We evaluated the association between alcohol intake during pregnancy and preterm delivery. Women attending routine antenatal care at Aarhus University Hospital, Denmark, from 1989-1991 and 1992-1996 were eligible. We included 18,228 singleton pregnancies in the analyses. We obtained prospective information on alcohol intake at 16 and 30 weeks of gestation, other lifestyle factors, maternal characteristics, and obstetrical risk factors from self-administered questionnaires and hospital files. For women with alcohol intake of 1-2, 3-4, 5-9, and > or =10 drinks/week the risk ratio (RR) of preterm delivery was 0.91 (95% CI = 0.76-1.08), 0.86 (95% CI = 0.64-1.15), 0.89 (95% CI = 0.52-1.52), and 2.93 (95% CI = 1.52-5.63), respectively, compared with intake of <1 drink/week at 16 weeks gestation, and 0.69 (95% CI = 0.56-0.86), 0.82 (95% CI = 0.60-1.13), 0.97 (95% CI = 0.58-1.64), and 3.56 (95% CI = 1.78-7.13) at 30 weeks. Adjustment for smoking habits, caffeine intake, age, height, pre-pregnant weight, marital status, occupational status, education, parity, chronic diseases, previous preterm delivery, mode of initiation of labor, and sex of the child did not change the conclusions, nor did restriction of the highest intake group to women drinking 10-14 drinks/week (RR = 3.41 (1.71-6.81) at 16 weeks and RR = 3.47 (1.64-7.35) at 30 weeks).     

吉林地区儿童先天性心脏病影响因素的病例对照研究

目的 分析吉林地区儿童先天性心脏病(CHD)的非遗传影响因素,寻找降低吉林地区儿童CHD患病风险的针对性策略。方法 选择2019—2020年吉林省出生缺陷上报系统发现的符合纳入标准并愿意配合的70对CHD患儿及其母亲作为病例组,选择同性别、年龄、地区的140对健康儿童及其母亲作为对照组进行1∶2病例对照配对。应用多因素Logistic回归分析模型分析儿童CHD的影响因素。结果 病例组和对照组儿童的性别、年龄分布差异无统计学意义(P>0.05),多因素分析结果显示：早产(OR=6.224)、父亲孕前3个月内饮酒(OR=2.476)、母亲孕前BMI≥25(OR=8.372)是儿童CHD的危险因素(P<0.05),孕期服用复合维生素(OR=0.342)是儿童CHD的保护因素(P<0.05)。结论 早产、父亲孕前3个月内饮酒和母亲孕前BMI≥25是吉林地区儿童CHD发病的危险因素,应重点关注早产儿心脏功能,加强对备孕夫妇保健知识的宣传教育,鼓励其戒烟戒酒、控制体重,做好孕前和孕期保健。     

Increased risk of preterm delivery in women residing near thermal power plants in Taiwan

In this article, the researchers studied the prevalence of preterm births for women living near thermal power plants. The prevalence of delivery of preterm birth infants was significantly higher among women living within 3 km of a thermal power plant than among women living within 3-4 km of a plant. After controlling for several possible confounders (including maternal age, season, marital status, maternal education, infant gender, and birth site), the adjusted odds ratio was 1.14 (95% confidence interval, 1.01-1.30) for delivery of preterm infants for women living close to the thermal power plants. These data provide further support for the hypothesis that air pollution can affect the outcome of pregnancy, although a semiecological study cannot confirm a direct causal relationship.     

Increased Risk of Preterm Delivery in Women Residing near Thermal Power Plants in Taiwan

In this article, the researchers studied the prevalence of preterm births for women living near thermal power plants. The prevalence of delivery of preterm birth infants was significantly higher among women living within 3 km of a thermal power plant than among women living within 3–4 km of a plant. After controlling for several possible confounders (including maternal age, season, marital status, maternal education, infant gender, and birth site), the adjusted odds ratio was 1.14 (95% confidence interval, 1.01–1.30) for delivery of preterm infants for women living close to the thermal power plants. These data provide further support for the hypothesis that air pollution can affect the outcome of pregnancy, although a semiecological study cannot confirm a direct causal relationship.