Working conditions, maternity legislation, and preterm birth

Controversies in the prevention of spontaneous preterm birth in asymptomatic women: an evidence summary and expert opinion

Preterm birth prevention is multifaceted and produces many nuanced questions. This review addresses six important clinical questions about preterm birth prevention as voted for by members of the UK Preterm Clinical Network. The questions cover the following areas: preterm birth prevention in 'low-risk' populations; screening for asymptomatic genital tract infection in women at high risk of preterm birth; cervical length screening with cerclage or vaginal pessary in situ; cervical shortening whilst using progesterone; use of vaginal progesterone in combination with cervical cerclage; and optimal advice about intercourse for women at high risk of preterm birth.

Risk factors for spontaneous preterm birth among Aboriginal and non-Aboriginal women in Manitoba

In the province of Manitoba, the incidence of preterm birth has been increasing and the rate is higher among Aboriginal than non-Aboriginal women. The purpose of this study was to identify risk factors for spontaneous preterm birth in Manitoba women, and to compare risk factors among Aboriginal and non-Aboriginal women. A case-control study was performed at two tertiary care hospitals in Winnipeg, Manitoba, Canada from October 1999 to December 2000. Cases delivered a live singleton infant at < 37 weeks gestation (n = 226; 36% Aboriginal), while controls delivered between 37 and 42 weeks gestation (n = 458; 38% Aboriginal). An interview was conducted with each subject on the postpartum unit, and information was collected from the health record. Using stratified analyses to control for race/ethnicity, several risk factors for preterm birth had a uniform effect measure across strata, while others demonstrated heterogeneity. After adjusting for other maternal characteristics in a multivariable logistic regression model, significant risk factors for all women included previous preterm birth, two or more previous spontaneous abortions, vaginal bleeding after 12 weeks gestation, gestational hypertension, antenatal hospitalisation, and prelabour rupture of membranes. In addition, potentially modifiable risk factors included low weight gain during pregnancy and inadequate prenatal care for all women, and high levels of perceived stress for Aboriginal women. These modifiable risk factors lend themselves to public health interventions, and should be targeted in future prevention efforts.

Outcomes and health status of socially disadvantaged women during pregnancy

We sought to examine the health status of disadvantaged pregnant women more broadly and to consider if poor maternal health predisposes a woman to an adverse birth outcome. We surveyed 250 women recruited from six health centers in the greater Boston area during their third trimester. The main predictor variables were maternal physical functioning (PF), emotional health (EH), and overall health status in the month prior to pregnancy. The main outcome variables were the decline of maternal PF and EH during pregnancy and adverse birth outcomes. Mean PF scores fell from 91.9 prior to pregnancy to 63.7 during the third trimester (mean scores transformed 0 to 100, where a higher score represents better health). EH remained unchanged during pregnancy. After adjustment, women with a preexisting medical condition reported a lower PF score prior to pregnancy (87.8 versus 94.5, p < 0.05). Poor PF prior to pregnancy or during the third trimester was associated with an increased risk of preterm labor (odds ratio 2.02, 95% confidence interval 1.03-3.97). This study is the first to employ general health status measures to examine changes in health during pregnancy. Our findings support the use of preconception care to improve the health status of disadvantaged women with pre-existing conditions. This study suggests that poor maternal health may predispose a woman to an increased risk of preterm labor.

The effect of heavy maternal workload on fetal growth retardation and preterm delivery. A study among southern Thai women

Heavy maternal workloads are considered to be hazardous to the fetus. The effects of physical activity during pregnancy on low birth weight (LBW), small for gestational age (SGA), and prematurity were assessed from a sample of 1797 women in a follow-up study at the antenatal clinic of two hospitals in southern Thailand. The women were interviewed twice, at 17 and 32 gestational weeks. Outcome data were obtained from medical records and the newborn gestational age determined using Dubowitz's score. The risk of SGA was elevated for women working > 50 hours/week, squatting in work, commuting > 1 hour/day, and having high psychological job demands; the risk of preterm delivery was increased with obstetrical complications. Women who worked long hours and had demanding work conditions had an elevated risk of giving birth to SGA infants but not of preterm delivery.