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ORIGINAL RESEARCH |
From the Department of Preventive Medicine, University of Kansas School of Medicine-Wichita, Wichita, Kansas; Department of Public Health Sciences, Wichita State University, Wichita, Kansas; and Georgia State Department of Public Health, Atlanta, Georgia.
Address reprint requests to: Linda M. Frazier, MD, MPH Department of Preventive Medicine University of Kansas School of Medicine-Wichita 1010 North Kansas Avenue Wichita, KS 67214 E-mail: lfrazier{at}kumc.edu
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Abstract |
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Methods: Data were analyzed from the Georgia Pregnancy Risk Assessment Monitoring System, a surveillance system that surveys new mothers about pregnancy risk factors, health behaviors, and birth-related outcomes. Employment during pregnancy was defined as work for pay for 10 hours or more per week.
Results: We studied 1635 women who were employed during pregnancy. A physician or nurse had advised 27.7% (95% CI 24.5%, 30.9%) of them to stop working during pregnancy. Independent predictors of receiving this advice were hospitalization (RR 2.3, 95% CI 1.7, 2.8) and history of previous preterm birth (RR 1.6, 95% CI 1.1, 2.2). Low birth weight (under 2500 g) occurred in 5.8% of women not advised to stop work, in 6.9% of women advised to stop work because of swelling, fatigue, stress, or another reason, and in 13.4% of women advised to stop work because of labor, high blood pressure, or vaginal bleeding (P < .001). Among women advised to stop working in the first through seventh months of pregnancy, 91.7% (95% CI 88.8, 94.5) delivered at 36 or more weeks’ gestation.
Conclusion: Work cessation during pregnancy was commonly recommended in this population and was associated with clinical risk factors and adverse birth outcomes. For some women it resulted in a long period of work absence before delivery.
Many pregnancies are uncomplicated and so there is no reason to advise the gravid woman to stop employment temporarily. Some women are advised to modify their activities because of pregnancy complications, such as early labor, preeclampsia, or other medical problems. Sometimes work is restricted because the job entails exposure to toxic chemicals or other hazards. Prolonged standing and other physical demands at work have been associated with 22–26% increase in risk of preterm birth, so those activities might be restricted during pregnancy.1–5
When there are pregnancy complications or job hazards, a work restriction is a type of therapy that is intended to improve fetal and maternal health or to prevent complications. As with any therapy, it would be useful have data on the effectiveness of prescribing work restrictions during pregnancy. Although there are many studies of occupational risk factors during pregnancy, a MEDLINE search from 1966 through 2000 using the search terms pregnancy and women and intervention studies; clinical trials and employment; or job, occupational, or work identified no reports on patient outcomes when these risk factors are modified. It would be challenging to implement randomized trials because prescribing work restrictions is already an accepted part of clinical practice. A useful preliminary step then is to characterize clinical practice by describing the frequency of the treatment and the characteristics of the patients who receive it. Therefore, we analyzed data from a large, population-based, stratified sample of women who were surveyed after giving birth. We focused on a major job restriction, cessation of work. This study sought to answer the following questions: how often were employed women advised by a health care provider to leave their job during pregnancy? What were the characteristics of the women who were advised to stop working?
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Materials and Methods |
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Information from 1996 and 1997 for singleton births was analyzed. These mothers represented 98.7% of the weighted study population for the study period. For each variable, there were missing data for 0–4% of mothers, except for intendedness of pregnancy and income, which were missing for 6% of women. No data were imputed; if data were missing, the mother was omitted from the analysis of that variable.
Recoding was done using the Statistical Package for the Social Sciences (SPSS version 9.0; SPSS Inc., Chicago, IL). Statistical analyses were performed using SUDAAN (Research Triangle Institute Inc., Cary, NC). All proportions are reported as weighted percentages. Continuous variables were compared by using t tests and proportions were compared using 
2 tests generated by SUDAAN. All tests were two-tailed with an alpha of 0.05. For proportions, 95% confidence intervals (CI) were calculated using the standard errors (SE) for each proportion, using the formula, 95% CI = proportion ± 1.96 x SE.
A logistic regression model for predicting advice to stop working during pregnancy was constructed by including all independent predictor variables that had P < .25 in univariable analyses. Then a stepwise backwards procedure was used to remove variables sequentially until the most parsimonious explanatory model was derived. The outcome in this study, the prevalence of advice to stop working, Po’, was frequent (27.7% of employed pregnant women). Odds ratios overestimate risk ratios when the outcome is frequent. Therefore to provide an estimate of relative risk (RR), the adjusted odds ratios (OR) and their 95% CI were corrected using the following formula7: RR = OR / [(1 - Po) + (Po x OR)].
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Results |
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Compared with other women in the sample, employed women were more likely to have a family income of more than $20,000 per year (52.4% compared with 47.6%, P < .001) and to use private insurance to pay for prenatal care (76.2% compared with 23.8%, P < .001). Employed women were more likely to have attended college (70.9% compared to 29.2%, P < .001) and to know that folic acid can prevent birth defects (66.0% compared with 34.0%, P = .003). Employed women were slightly more likely to be married (52.7% compared with 47.6%, P < .001). They were also more likely to state that they wanted to be pregnant then or sooner (65.8% compared with 34.2%, P = .019) instead of wanting to be pregnant later or never. Employed women also were more likely to have begun prenatal care in the first trimester (67.5% compared with 32.5%, P < .001). There were no differences by employment status in hospitalization during pregnancy or in the gestational age or birth weight of infants.
Among employed women, age was less than 20 years in 11.0%, 20–29 years in 54.3%, and more than 29 years in 34.7%. White race was reported by 66.2% of the group of employed mothers, black race was reported by 32.0%, and another race by 1.7%. Low birth weight occurred in 7.2% (95% CI 6.4, 8.0) of the infants born to employed women.
A physician or nurse reportedly advised 27.7% (95% CI 24.5, 30.9) of employed pregnant women to stop working during pregnancy. The relationships between various maternal characteristics and advice to stop working are shown in Table 1
. There was no difference in maternal age between the women who were advised to stop working and those who were not (mean age 27.1 years compared with 26.9 years, respectively, P = .6). Logistic regression analysis identified hospitalization during pregnancy (RR 2.30, 95% CI 1.74, 2.77) and history of previous preterm birth (RR 1.62, 95% CI 1.10, 2.18) as independent predictors of being told to stop working. Paying for prenatal care using private insurance contributed to the explanatory power of the model, but this variable did not reach statistical significance (RR 1.6, 95% CI 0.97, 1.8). The model containing these three variables accounted for 9.4% of the variance in advice to stop working (r2 = .094, P < .001).
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). Women who received advice to stop working because of labor, high blood pressure, or vaginal bleeding had a greater risk of delivering an infant who was premature or low birth weight, and there was a trend toward increased risk of the infant being admitted to the neonatal intensive care unit.
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). Among women who were advised to stop working for any reason, half reported that they last worked in seventh month of pregnancy or earlier (52.5%, 95% CI 45.8%, 59.2%). Among women who stopped working in the seventh month of pregnancy or earlier, 91.7% (95% CI 88.8%, 94.5%) delivered at 36 or more weeks’ gestation. |
Discussion |
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Advice to stop working was associated with adverse pregnancy outcomes. This finding suggests medically prescribed leaves of absence from work were not arbitrary, but were associated with women at clinical risk. Because family income was not associated with medical advice to stop working, it appears that prenatal care providers did not prescribe work leave for social reasons among women who could tolerate loss of income. Instead, these data suggest that a sizable minority of pregnant women might require antenatal medical leave because of risk factors and pregnancy complications.
A strength of this study is that the data were collected as part of the Pregnancy Risk Assessment Monitoring System, a large, high-quality, population-based survey using standard methods. The response rate was very good, the amount of missing data was very low, and the birth outcomes were verified from birth certificates. Although the population included only mothers in Georgia, the study was representative of the state. A limitation is that the work variables were self-reported. The effect of reporting bias on the main outcome, being advised by a health care provider to stop paid work, is not known. Because there is no stigma attached to receiving advice about employment, substantial reporting bias is probably not likely.
The relationships of hospitalization and history of preterm birth to advised work cessation are plausible, but the trend toward more stop work orders among women with private health insurance is unexplained. Among women who did not have the two statistically significant predictor variables, hospitalization and previous preterm birth, more than one fifth were still advised to leave work (Table 1). Because this proportion is high, a future study is warranted to assess the effects of other clinical characteristics on physicians’ recommendations to stop working, as well as factors related to the employer and the type of work.
A previous study suggested significant limitations of activity are prescribed relatively frequently during pregnancy. Goldenberg and colleagues2 found 18% of women were placed on bed rest during pregnancy. Extended bed rest would require stopping work. In another study using case vignettes, physicians prescribed bed rest if the woman had risk factors for preterm birth, chronic hypertension, placenta previa, or concurrent preterm labor.3
Preterm birth and low birth weight are increasingly common in the United States,8 and so many pregnant women might require leave during pregnancy because of risk factors or warning signs of these conditions. Because of the morbidity and mortality associated with preterm birth, it is understandable that physicians would restrict job activities among atrisk pregnant women to reduce this outcome. Because this advice was given to more than one in four employed pregnant women, research on its efficacy is warranted, particularly among subgroups of women who are not at high risk.
Advising pregnant women to leave work could have adverse effects. Although some women might be granted medical leave by their employers, others could lose their jobs. The Family and Medical Leave Act protects some pregnant workers’ jobs during an antenatal leave, allowing 12 weeks of leave for serious medical conditions. Whether increased risk alone constitutes a serious medical condition could be interpreted in various ways by companies.9 In addition, the leave is unpaid and 40.5% of employees in the private sector are not eligible for this leave because they work for small companies.10
Because of the 12-week limit under the Family and Medical Leave Act, taking medical leave during pregnancy might reduce the amount of time available for maternity leave after the infant is born. Half of the women in our study who were advised to stop work, last worked in the first through the seventh month of pregnancy; almost all of those women delivered at 36 weeks or later. This suggests an important minority of pregnant women might be out of work for a prolonged period before birth. To preserve their jobs, women who are in this situation might take shorter postpartum leaves, perhaps compromising their time for physiologic recovery, infant bonding, duration of breast feeding, and other important outcomes.11,12 Lack of data on the proportion of pregnant women who must leave their jobs for health reasons before delivery might be one reason why the Family and Medical Leave Act provides for fewer weeks of job protection than are available to working pregnant women in Europe.13,14 Policy makers in the United States might assume that few women need extended antenatal leave and that 12 weeks of postnatal leave are sufficient.
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Footnotes |
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Received September 12, 2000. Received in revised form December 22, 2000. Accepted January 31, 2001.
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References |
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2. Goldenberg RL, Cliver SP, Bronstein J, Cutter GR, Andrews WW, Mennemeyer ST. Bed rest in pregnancy. Obstet Gynecol 1994;84: 131–6.
3. Maloni JA, Cohen AW, Kane JH. Prescription of activity restriction to treat high-risk pregnancies. J Womens Health 1998;7:351–8.[Medline]
4. McMartin KI, Chu M, Kopecky E, Einarson TR, Koren G. Pregnancy outcome following maternal organic solvent exposure: A meta-analysis of epidemiologic studies. Am J Ind Med 1998;34: 288–92.[Medline]
5. Mozurkewich EL, Luke B, Avni M, Wolf FM. Working conditions and adverse pregnancy outcome: A meta-analysis. Obstet Gynecol 2000;95:623–35.
6. Colley-Gilbert BJ, Johnson CH, Morrow B, Gaffield ME, Ahluwalia I. Prevalence of selected maternal and infant characteristics, Pregnancy Risk Assessment Monitoring System (PRAMS), 1997. Morbid Mortal Wkly Rep CDC Surveill Summ 1999;48:1–37.
7. Zhang J, Yu KF. What’s the relative risk? A method of correcting the odds ratio in cohort studies of common outcomes. JAMA 1998;280:1690–1.
8. United States Department of Health and Human Services. Healthy People 2010, Conference Edition. Washington, DC: US Government Printing Office 2000;16–33.
9. Stave GM. Laws and regulations addressing workplace reproductive hazards. In: Frazier LM, Hage ML, eds. Reproductive hazards of the workplace. New York: John Wiley & Sons, 1998:87–95.
10. Centers for Disease Control and Prevention, National Center for Health Statistics. Women: Work and health. Series 3: Analytical and epidemiological studies, no. 31. Hyattsville, MD: DHHS Publication No. (PHS) 97-1415, 1997.
11. Gjerdingen DK, McGovern PM, Chaloner KM, Street HB. Women’s postpartum maternity benefits and work experience. Fam Med 1995;27:592–8.[Medline]
12. Fein SB, Roe B. The effect of work status on initiation and duration of breast-feeding. Am J Public Health 1998;88:1042–6.
13. Taskinen HK, Olsen J, Bach B. Experiences in developing legislation protecting reproductive health. J Occup Environ Med 1995;37: 974–9.[Medline]
14. Kamerman SB. From maternity to parental leave policies: Women’s health, employment and child and family well-being. J Am Womens Assoc 2000;55:96–9.
This article has been cited by other articles:
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  M J Saurel-Cubizolles, J Zeitlin, N Lelong, E Papiernik, G C Di Renzo, and G Breart Employment, working conditions, and preterm birth: results from the Europop case-control survey J. Epidemiol. Community Health, May 1, 2004; 58(5): 395 - 401. [Abstract] [Full Text] [PDF]
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