Are there common triggers of preterm deliveries?

Abstract

Objective: To assess the effect(s) of transient events which are perceived as stressful on the inseption of preterm delivery. Design: A case-control study, with immature infants as cases and borderline term babies as controls. Setting: A teaching maternity hospital in Athens. Population: All infants born at less than 37 weeks of gestation, during a twelve-month period. Methods: Information was collected about maternal socio-demographic and lifestyle characteristics, clinical variables and stressful events occurring within two weeks prior to delivery. Main outcome measures: Factors affecting the risk of preterm delivery. Results: Extreme prematurity (<33 weeks) is more common among younger (<25 years of age) and older (>29 years of age) women and is positively associated with parity, body mass index and smoking, whereas it is inversely associated with educational level, regular physical exercise and serious nausea/vomiting. After controlling for these factors, however, only coitus during the last weeks of pregnancy had a significant triggering effect on prematurity (P = 0.004, odds ratio 3.21, 95% CI 1.45 to 7.09 for very immature babies, and P = 0.04, OR = 2.20, 95% CI 1.03 to 4.70 for immature babies). On the contrary, several events perceived as stressful, such as illness of relatives or friends, husband's departure, loss of employment, were unrelated to the onset of premature labour. Conclusions: Coitus during the last few weeks of pregnancy appears to increase the risk of preterm delivery, while a possible detrimental effect of physical exertion seems more limited. Stressful events should not receive undue attention as possible causes of preterm delivery.