Healthy worker effect and pregnancy: role of adverse obstetric history and social characteristics.

Data from a survey conducted in 1981 on a national sample of 5508 births in France were used to analyse the role of a history of previous adverse pregnancy outcome (spontaneous abortion, perinatal death or adverse fetal condition) in the selection mechanisms of women with regard to occupational activity, and the impact on the relation between work and preterm delivery. The study, carried out separately in each parity group, showed that occupational activity was associated with a more favourable outcome for women of parity one: the preterm delivery rate was significantly higher among women who had never worked than among those who continued working during pregnancy. However, the hypothesis of a "healthy worker effect" linked to a history of adverse obstetric outcome was not confirmed in this study. A selection effect of women from a history of spontaneous abortions was observed, but these were not linked to preterm delivery. Among multiparous women, a history of perinatal death or adverse fetal condition did not seem to modify women's behaviour towards their work. Selection mechanisms of women towards occupational activity according to sociodemographic factors were also analysed and showed that the higher percentage of younger women among those who had never worked explained the higher rate of preterm delivery in that group.     

Outcome of pregnancy in relation to irregular and inconvenient work schedules.

The relation between irregular and inconvenient working hours and the outcome of pregnancy was studied among women employed at a hospital in Sweden some time between 1980 and 1984. A questionnaire was distributed to 807 women; 81% replied. The pregnancies were divided into six groups with respect to work schedules during pregnancy. A slightly, but not significantly, increased risk of miscarriage was found in women who worked irregular hours or rotating shifts compared with women who worked only during the day (RR = 1.44, 95% confidence interval 0.83-2.51). Infants of non-smoking mothers who worked irregular hours had significantly lower birth weights than infants of non-smoking women working day time only. This difference was largest at birth order 2+. Similar results were found for infants of this birth order whose non-smoking mothers worked evenings or rotating shift.     

Outcome of pregnancy in relation to irregular and inconvenient work schedules

The relation between irregular and inconvenient working hours and the outcome of pregnancy was studied among women employed at a hospital in Sweden some time between 1980 and 1984. A questionnaire was distributed to 807 women; 81% replied. The pregnancies were divided into six groups with respect to work schedules during pregnancy. A slightly, but not significantly, increased risk of miscarriage was found in women who worked irregular hours or rotating shifts compared with women who worked only during the day (RR = 1.44, 95% confidence interval 0.83-2.51). Infants of non-smoking mothers who worked irregular hours had significantly lower birth weights than infants of non-smoking women working day time only. This difference was largest at birth order 2+. Similar results were found for infants of this birth order whose non-smoking mothers worked evenings or rotating shift.     

Who are the Women Who Work in Their Last Month of Pregnancy? Social and Occupational Characteristics and Birth Outcomes of Women Working Until the Last Month of Pregnancy in France

Introduction The prenatal leave law in France protects women during pregnancy and their employment. We aimed to estimate the proportion of women who worked late in their pregnancy, to analyze the occupational, social and medical factors associated with late prenatal leave and to compare the pregnancy outcome of these women and those who left earlier in the pregnancy. Methods The sample was extracted from the 2010 French National Perinatal Survey. All women who delivered within a 1-week period were interviewed before discharge from the maternity unit. Women with a singleton live birth at or after 37 weeks’ gestation and who were working during pregnancy (n = 8463) were included. Data were collected on employment, date of leave, and sociodemographic and medical characteristics. Results Overall, 328 women (3.9 %) took a late prenatal leave (at or after 37 weeks’ gestation). Women who left late were older than 30 years old, with a high educational level and were living in an urban area. Being self-employed and having a managerial or upper-intellectual occupation was highly associated with late leave, before and after controlling for relevant variables. Perinatal and delivery outcomes were similar for women who took a late leave and those who left before 37 weeks’ gestation. Discussion Occupational characteristics are the main determinants of late prenatal leave. Women working in the last month of pregnancy had a favorable social and occupational situation and did not did not experience an adverse pregnancy or birth outcome. Other studies are needed to understand the reasons for late leave and evaluate the post-partum fatigue and health of these women.     

Likelihood of Emergency Contraception Use Among African-American Women at Risk of Adverse Birth Outcomes

Nearly a half million infants in the United States are born preterm or with low birth weight each year. Providing women who have had a prior adverse birth outcome with access to family planning can help reduce the incidence of subsequent high-risk pregnancies and adverse outcomes. One effective option to prevent unintended pregnancy for women with a prior adverse birth outcome who either do not use contraception consistently or whose contraception fails is emergency contraception (EC). The purpose of our study was to understand willingness to use EC among African-American women who recently had an adverse birth outcome. The Healthy Births Healthy Communities (HBHC) Interconceptional Care Project (ICCP) targeted high-risk African-American women from two low-income Chicago neighborhoods who recently had an adverse birth outcome. The aim of HBHC ICCP was to improve participants’ future birth outcomes by providing medical and social services and helping women to clarify their reproductive life goals. Information about participants’ pregnancy intentions and willingness to use EC was measured in an interview shortly after enrollment into the study. Over 90 % of the 131 women in our study either did not want to become pregnant or did not know if they wanted to become pregnant within the next 2 years. These women had 4.4 times higher odds of reporting willingness to use EC as compared to women who reported a desire to become pregnant within the next 2 years (75.6 vs. 50.0 %, respectively; AOR: 4.4; 95 % CI 1.1, 17.6). EC is an essential part of the reproductive toolkit for women at high risk of adverse birth outcomes who are not intending pregnancy, along with reproductive life planning and use of effective contraception.     

The relationship of interpregnancy interval to infant birthweight and length of gestation among low-risk women, Georgia

To examine the association between interpregnancy interval and low birthweight (< 2500 g), preterm delivery (< 37 weeks' gestation), and inadequate fetal growth, we studied a population-based sample of 23 388 white and 4885 black women at low risk for adverse pregnancy outcomes who delivered their first and second infants in Georgia from 1980 to 1992. We used fetal death and livebirth certificates. The interpregnancy interval was the time from delivery to the woman's next conception. For each pregnancy outcome, we stratified by race and used logistic regression to assess the association between interpregnancy interval and outcome, while controlling for confounders. Intervals <6 months were observed for 3.7% of white women and 7.0% of black women and intervals 48 months were seen for 16.8% of white women and 24.8% of black women. Results from logistic regression showed that, for both races, interpregnancy interval was associated with low birth-weight and preterm delivery. Nearly all of the increased risk occurred in intervals < 6 months or 48 months. The magnitude of the increase in risk associated with these intervals ranged from modest to moderate and was similar for black and white women. Because short interpregnancy intervals are rare and are weak risk factors among low-risk women, efforts to lengthen interpregnancy intervals are unlikely to reduce substantially their rates of adverse pregnancy outcomes.     

Evidence from the National Survey of Family Growth. Work during pregnancy and subsequent hospitalization of mothers and infants.

Large and increasing proportions of women work late into pregnancy and resume work soon after delivery. If work in those periods injures their health or that of their infants, this trend would be of public health concern. Data on ever-married primaparas from the National Survey of Family Growth conducted by the National Center for Health Statistics were used to investigate the relationship between working in the last trimester of pregnancy and two indicators of illness--hospitalization of women for complications of pregnancy and hospitalization of their infants during the first year of life. Hospitalization of the mother or child occurred for 15.0 percent of the primaparas. For primaparas who worked in the last trimester of pregnancy, the percentage was slightly higher--17.1 percent. In two groups, black women and women without hospital insurance for delivery, the percentage of mothers or infants hospitalized was much higher among the mothers who worked in the third trimester than among those who did not. The association of working late in pregnancy with higher rates of hospitalization does not mean, necessarily, that working is a cause of hospitalization. It does indicate, however, the need for epidemiologic and medical research on the relationship.     

Smoking in early gestation or through pregnancy: a decision crucial to pregnancy outcome

OBJECTIVE: To assess maternal risk profile and pregnancy outcome of women who continued to smoke, reduced smoking to less than five cigarettes per day or did not smoke during pregnancy. METHODS: We analyzed a population-based database of 26,414 singleton pregnancies from 1989 to 2001. Odds ratios (ORs) for adverse pregnancy outcomes were obtained from multiple logistic regression models. RESULTS: The prevalence of smoking in early pregnancy was 25.7% and went down to 12.7% at 20 weeks of pregnancy. Women who smoked were more often young, primiparous or unmarried, used alcohol and more often had prior pregnancy terminations than women who did not smoke. Women who reduced smoking were mostly primiparous, and they also quit using alcohol. Continuing to smoke was associated with elevated risks of small-for-gestational-age infants (SGA) (OR 2.11), preterm birth (OR 1.15) and perinatal death (OR 1.15). SGA was avoided by reducing smoking, but not prematurity (OR 1.18) or elevated risk of perinatal death (OR 1.18). CONCLUSION: Smoking in early gestation and through pregnancy is associated with adverse pregnancy outcomes, and some of the harmful effects can be avoided by reducing smoking, although the behavioral risk profile of those who reduced smoking is closer to that of smokers than of non-smokers.     

The risk of miscarriage and birth defects among women who use visual display terminals during pregnancy

Use of visual display terminals (VDTs) was examined in a case-control study of pregnancy outcome among 1,583 pregnant women who attended three Kaiser Permanente obstetrics and gynecology clinics in Northern California, 1981-1982. We found a significantly elevated risk of miscarriage for working women who reported using VDTs for more than 20 hr per week during the first trimester of pregnancy compared to other working women who reported not using VDTs (odds ratio 1.8, 95% CI: 1.2-2.8). This risk could not be explained by age, education, occupation, smoking, alcohol consumption, or other maternal characteristics. No significantly elevated risk for birth defects was found among working women although odds ratios were 1.4 for both moderate and high VDT exposure, compared with no exposure (95% CI: 0.7-2.7 and 0.7-2.9, respectively). One possible explanation for these findings is that women who had adverse pregnancy outcomes may have overreported their exposures to VDTs and/or women with normal births may have underreported theirs. The findings may also be due to unmeasured factors confounded with high VDT use such as poor ergonomic conditions or job-related stress. That VDTs themselves are hazardous to the pregnant operator remains a possibility. Our results underscore the need for large cohort studies of working women that will provide objective measures of VDT exposures, ergonomic factors, and stress.     

Induced abortion: not an independent risk factor for pregnancy outcome, but a challenge for health counseling

PURPOSE: Low birth weight (LBW), preterm births, abnormal placentation, and miscarriages have been associated with prior induced abortions. An incidence-related effect has been suggested. The objective of this study is to assess the effects of prior induced abortions on obstetric risk factors and pregnancy outcome in conditions of free high-standard maternity care used by almost the entire pregnant population in Finland. METHODS: We analyzed a population-based database including 26,976 singleton pregnancies from 1989 to 2001, of which 2364 were among women with one prior induced abortion and 355 women had had at least two prior induced abortions. Data included maternal risk factors, pregnancy characteristics, and obstetric outcome measures and were based on results of a self-administered questionnaire at 20 weeks of pregnancy and clinical records. Odds ratios (ORs) concerning pregnancy outcomes were calculated in multiple logistic regression analysis. RESULTS: Induced abortions were associated with several known pregnancy risk factors; specifically, maternal age older than 35 years, unemployment, unmarried status, low educational level, smoking, alcohol consumption, overweight condition, and chronic illnesses. Preterm birth (OR, 1.19; 95% confidence interval, 1.01-1.41) in women with one prior abortion (7.3% versus 6.2%) and LBW (OR, 1.54; 95% confidence interval, 1.02-2.32) in women with two or more prior abortions (7.0% versus 4.7%) appeared to be more common, but after logistic regression analysis, we found no evidence of adverse pregnancy outcomes. CONCLUSIONS: Induced abortion is not an independent risk factor for adverse obstetric outcome. Marked health behavioral pregnancy risks are associated with prior induced abortions. Health counseling of these women is a challenge, but this objective has not yet been achieved.     

Pregnancy outcome among working women

The influence of occupational factors on the outcome of pregnancy was investigated in a prospective study of 3901 women who worked during their pregnancy and received prenatal care in Orebro County from October 1980 to June 1983. Data on occupational factors, social circumstances, and life-style factors were obtained from questionnaires. There were no significant differences in the incidence of adverse pregnancy outcome (spontaneous abortion, perinatal death, birth defects, or low birthweight) between the nine occupational categories used when nonoccupational factors were accounted for. No increased risk was found for exposure to organic solvents, but the adjusted risk ratio of adverse outcome was 1.28 (95% CI 0.91-1.80) for "other chemical exposures." The work conditions in this county have been generally favorable in recent years, and the results therefore cannot be generalized to conditions with higher exposures. Methodological problems such as misclassification of exposure and the possible bias resulting from different rates of legal abortions among occupational groups are discussed.     

Spontaneous abortion among women using video display terminals

This case-base study with a source population of 214 108 commercial and clerical workers investigated the risk of adverse pregnancy outcome among women working with a video display terminal (VDT) in Denmark. A subpopulation was obtained by register linkage between a trade union membership file, the Medical Birth Register, and the National Register of In-Patients. In two years 24,352 pregnancy outcomes were registered, 2248 spontaneous abortions were recorded, and a base sample of 2252 pregnancies was randomly selected. Data on VDT use, job stress, ergonomic factors, and life-style factors were collected with questionnaires sent to 6212 women and 426 employers. There was no increased risk of medically verified spontaneous abortion among women with VDT use. The relative risk for women exposed to any degree of use was 0.94 (95% confidence interval 0.77-1.14). Ergonomic work load and job stress were not confounders.     

Antenatal Maternity Leave and Childbirth Using the First Baby Study: A Propensity Score Analysis

BackgroundMost employed American women work during pregnancy and continue working through the month they deliver. Yet, few studies estimate the relationship between maternity leave taken during pregnancy and maternal health. We evaluate the association of antenatal leave (ANL) uptake with obstetric outcomes, assessing the potential role of protective and adverse selection pathways on this relationship.MethodsWe sample 1,740 employed women who delivered at term from the First Baby Study, a prospective cohort of nulliparous women in Pennsylvania. We use propensity scores to estimate the relationship between ANL and negative delivery outcomes (labor induction, long labor duration, unplanned cesarean delivery, and self-reported negative birth experience). We estimated propensity scores using a range of employment, health, and sociodemographic variables.ResultsOne-half of the sampled women worked until the day before or day of delivery. Women who stopped working at least 2 days before delivery experienced 16% more negative delivery outcomes, on average, than women who worked until delivery, driven largely by a 25% higher predicted probability of unplanned cesarean section deliveries. These robust findings hold up to a range of sensitivity analyses and demonstrate selective mechanisms operating in ANL uptake.ConclusionOur findings suggest that, even after controlling for an extensive set of observable employment, health, and sociodemographic characteristics, women who take ANL continue to differ in unobserved characteristics that lead to negative delivery outcomes. Like most U.S. states, Pennsylvania does not grant paid maternity leave. In a context of limited maternity leave availability, only relatively unhealthy women take ANL.     

Spontaneous abortion in dry cleaning workers potentially exposed to perchloroethylene.

OBJECTIVES: To investigate the association between spontaneous abortion and work within dry cleaning units in the United Kingdom where the solvent perchloroethylene is used. METHODS: A retrospective occupational study of reproductive outcome in 7305 women aged 16 and 45 years, who were currently or previously employed in dry cleaning or laundry units in the United Kingdom. Data on workplace exposures and reproductive outcome were obtained by postal survey. A sample of reported spontaneous abortions was validated from medical records. Machine operator versus non-operator was used as a surrogate for exposure to perchloroethylene in dry cleaning units as no data on individual doses were available for women in this study. RESULTS: The response rate was higher for current workers of dry cleaning units (78%), than for past workers of dry cleaning units (46%). Similarly, the response for current laundry workers (65%) was higher than that for past laundry workers (40%). Overall, the reproductive characteristics of the respondents were similar to expectation. Examination of exposure at the time of pregnancy, however, showed that the rate of spontaneous abortion varied according to the type of work the women did during the pregnancy or in the three months before conception: being lowest for pregnancies not exposed to either dry cleaning or laundry work (10.9%), higher for those exposed to laundry work (13.4%), and higher still for those exposed to dry cleaning work (14.8%). Within the group of pregnancies exposed to dry cleaning, the proportion was higher if the woman reported that she worked as an operator at the time of the pregnancy (17.1%) rather than as a non-operator (11.6%). Adjusted odds ratios for the period 1980-95 showed that the risk was over 50% higher in operators than non-operators (p = 0.04). The physical demands of the two jobs are likely to be similar. A higher risk was found when work as a dry cleaning operator was compared with no work in either dry cleaning or laundry units during pregnancy. Exposure to dry cleaning as a non-operator was not associated with any excess risk. CONCLUSIONS: Women who worked in dry cleaning shops at the time of their pregnancy or in the three months before who described themselves as operators were about half as likely again to report that their pregnancy ended in a spontaneous abortion than women who described themselves as non-operators.     

Uptake and safety of Hepatitis B vaccination during pregnancy: A Vaccine Safety Datalink study

IntroductionHepatitis B virus (HBV) infection acquired during pregnancy can pose a risk to the infant at birth that can lead to significant and lifelong morbidity. Hepatitis B vaccine (HepB) is recommended for anyone at increased risk for contracting HBV infection, including pregnant women. Limited data are available on the safety of HepB administration during pregnancy.ObjectivesTo assess the frequency of maternal HepB receipt among pregnant women and evaluate the potential association between maternal vaccination and pre-specified maternal and infant safety outcomes.MethodsWe examined a retrospective cohort of pregnancies in the Vaccine Safety Datalink (VSD) resulting in live birth outcomes from 2004 through 2015. Eligible pregnancies in women aged 12–55 years who were continuously enrolled from 6 months pre-pregnancy to 6 weeks postpartum in VSD integrated health systems were included. We compared pregnancies with HepB exposure to those with other vaccine exposures, and to those with no vaccine exposures. High-risk conditions for contracting HBV infection were identified up to one-year prior to or during the pregnancy using ICD-9 codes. Maternal and fetal adverse events were also evaluated according to maternal HepB exposure status.ResultsAmong over 650,000 pregnancies in the study period, HepB was administered at a rate of 2.1 per 1000 pregnancies (n = 1399), commonly within the first 5 weeks of pregnancy. Less than 3% of the HepB-exposed group had a high-risk ICD-9 code indicating need for HepB; this was similar to the rate among HepB unvaccinated groups. There were no significant associations between HepB exposure during pregnancy and gestational hypertension, gestational diabetes, pre-eclampsia/eclampsia, cesarean delivery, pre-term delivery, low birthweight or small for gestational age infants.ConclusionsMost women who received maternal HepB did not have high-risk indications for vaccination. No increased risk for the adverse events that were examined were observed among women who received maternal HepB or their offspring.     

Pregnancy outcomes with an IUD in situ: a systematic review

BackgroundWhile intrauterine devices (IUDs) provide highly effective contraception, pregnancies among IUD users do rarely occur. The objective of this systematic review is to assess the evidence about risks for adverse pregnancy outcomes among women who conceive with an IUD in situ.MethodsWe searched MEDLINE, POPLINE, EMBASE and LILACS databases from inception through April 2011 for peer-reviewed articles containing evidence related to pregnancy outcomes among women who conceived while using copper (Cu) and levonorgestrel-releasing (LNG) IUDs.ResultsNine articles met our inclusion criteria. Women with retained IUDs were at the greatest risk of adverse pregnancy outcomes, including spontaneous abortion, preterm delivery, septic abortion and chorioamnionitis. Cu-IUD removal decreased risks but not to the baseline risk of pregnancies without an IUD. One case series examined the LNG-IUD; when left in situ, 8 in 10 ended in spontaneous abortions.ConclusionPregnancies complicated by a remaining IUD in situ were at greater risk of adverse pregnancy outcomes. Early IUD removal appeared to improve outcomes but did not entirely eliminate risks.     

Pregnant women''s working conditions and their changes during pregnancy: a national study in France.

In a study of 2387 employed women who had worked for more than three months of their pregnancy the data were extracted from a survey carried out on a national sample of births in France in 1981. Manual, service and shop workers had a higher preterm delivery rate than professional, administrative, or clerical workers. Assembly line work was associated with a higher preterm delivery rate even when production workers only were considered. Cumulated physically tiring working conditions--standing work, carrying of heavy loads, assembly line work, and considerable physical effort--were related to higher preterm delivery and low birthweight rate. During pregnancy, sickness absences were commoner when the working conditions were arduous. Changes in the working conditions were less clearly related to arduous work than sick leaves; they were not significantly more frequent for standing work or for assembly line work. Refusals from employers to grant favourable arrangements were more frequent when the working conditions were tiring and sick leaves were more common among women whose requests had been refused.     

Pregnant women's working conditions and their changes during pregnancy: a national study in France

In a study of 2387 employed women who had worked for more than three months of their pregnancy the data were extracted from a survey carried out on a national sample of births in France in 1981. Manual, service and shop workers had a higher preterm delivery rate than professional, administrative, or clerical workers. Assembly line work was associated with a higher preterm delivery rate even when production workers only were considered. Cumulated physically tiring working conditions--standing work, carrying of heavy loads, assembly line work, and considerable physical effort--were related to higher preterm delivery and low birthweight rate. During pregnancy, sickness absences were commoner when the working conditions were arduous. Changes in the working conditions were less clearly related to arduous work than sick leaves; they were not significantly more frequent for standing work or for assembly line work. Refusals from employers to grant favourable arrangements were more frequent when the working conditions were tiring and sick leaves were more common among women whose requests had been refused.     

Characteristics of maternal employment during pregnancy: effects on low birthweight.

BACKGROUND: Although maternal employment is considered a risk factor for low birthweight (LBW), the manner in which employment might affect birthweight is poorly understood. In this analysis, selected characteristics of employment during pregnancy were examined for effects on pregnancy outcomes. METHODS: Work characteristics included the number of hours per week, physical activities, and environmental conditions. The outcomes of interest were fetal growth retardation (less than 2500 grams at term) and preterm delivery (less than 37 weeks). The study population consisted of 2711 non-Black, married mothers who participated in the 1980 National Natality Survey (NNS). The NNS data were merged with data from the 1977 revision of The Dictionary of Occupational Titles (DOT) from which measures of occupational physical activities and environmental exposures were obtained. Logistic regression was used in the analysis. RESULTS: Those who worked 40 or more hours per week were more likely than women who worked fewer hours to have a low birthweight delivery at greater than or equal to 37 weeks. No physical or environmental characterics of work were associated with low birthweight or preterm delivery. CONCLUSIONS: Non-Black married American women may face a risk of delivering low-birthweight babies at or near term only if they work 40 or more hours each week. However, the lack of risk associated with other characteristics of work may be a function of measurement error in the DOT data source or of low levels of exposure in the analysis population.