Diabetes and Premature Delivery: Etiology and Risk Factors 

Avi Beigelman, Arnon Wiznitzer, Ilana Shoham-Vardi, Hilel Vardi, Gershon Holtcberg, Moshe Mazor

Depts. of Obstetrics and Gynecology and of Epidemiology and Health Services Evaluation, Soroka Medical Center and Faculty of Health Science, Ben-Gurion University of the Negev, Beer Sheba

Preterm birth is the leading cause of perinatal morbidity and mortality, while preterm labor and delivery in diabetes mellitus (DM) carries an increased risk of perinatal complications. We investigated the hypothesis that DM (gestational and pregestational) is an independent risk factor for preterm birth and evaluated the hypothesis that the risk factors for preterm birth in diabetics are different from those in non-diabetics.

The study population consisted of all singleton deliveries at this hospital between 1990-1997. Excluded were those of mothers who had not had prenatal care, or who had only partial care or multiple gestations. There were 3 subgroups: 834 women with pregestational DM, 3,841 with gestational DM, and 66,253 non-diabetics.

The combined spontaneous and induced preterm delivery rate was determined in each subgroup. Potential risk factors for spontaneous preterm deliveries were assessed by a univariate model. A logistic regression model was used to assess the unique contribution of DM (gestational and pregestational) to preterm delivery in the presence of the other risk factors, and to compare risk factors for preterm delivery between subgroups.

The prevalence of spontaneous preterm delivery was: 7.1% in non-diabetics, 10.0% in those with gestational DM and 25.5% in those with pregestational DM. When adjusted by a multivariate model for other risk factors for preterm delivery, DM still remained an independent risk factor for spontaneous preterm delivery (gestational DM: odds ratio 1.28, 95% CI: 1.1-1.48; pregestational diabetes: odds ratio 3.4, 95% CI: 2.65-4.36).

The main difference in risk factors for preterm birth between the 3 subgroups was the amount of amniotic fluid. Polyhydramnios was an independent risk factor for preterm delivery in non-diabetics and in pregestational DM, but not in gestational DM. On the other hand, oligohydramnios was associated with a higher risk for preterm delivery only in gestational DM compared to non-diabetics.

DM (gestational and pregestational) is an independent risk factor for spontaneous preterm delivery. Polyhydramnios is an independent risk factor for preterm delivery in pregestational but not in gestational DM. Oligohydramnios is a greater risk factor for preterm delivery in gestational DM compared to non-diabetics.

Relationship Between Preterm Birth and Exertion During Pregnancy

S. Gazit-Nissim, E. Sheiner, M. Mazor, I. Shoham-Vardi

Depts. of Obstetrics and Gynecology, Epidemiology and of Health Services Evaluation, Soroka-University Medical Center, and Ben-Gurion University of the Negev, Beer Sheba

The relationship between physical activity at home and at work during pregnancy and preterm birth was studied. Using a case-control design, 99 women who delivered preterm were compared with 189 women who had term deliveries. The risk of preterm birth was tested in relation to characteristics of work in and outside the home. All women were interviewed post-partum before discharge.

There were no statistically significant differences between the groups in relation to sociodemographic and obstetrical factors, but level of education was significantly lower in the study group versus the control group (p=0.001).

Women who delivered preterm had devoted less time 3 months prior to delivery to household chores (mean of 3.7 hours vs. 4.8 hours in the control group, p=0.002). They also had spent less time walking around the home than the controls (1.2 vs. 1.5 hours, p=0.02). There were no differences between the groups in relation to physical activity outside the home, not during working hours, nor in duration of work. Significantly fewer women who delivered preterm were active in sports (odds ratio 0.22; 95% confidence interval 0.50-0.65; p=0.002).

A low level of education was significantly related to the risk of preterm birth, which may have resulted from lesser compliance with their physician's recommendations. It appears that in women not used to significant physical activity but who had access to adequate prenatal care, physical effort during pregnancy was not related to a higher risk of preterm birth.