Gender and preterm birth: Is male fetal gender a clinically important risk factor for preterm birth in high-risk women?

Gender differences in several adverse pregnancy outcomes have been described, including preterm labour and delivery. In the low risk population, the male fetus is at significantly higher risk of spontaneous preterm birth. OBJECTIVES: Our objective was to examine the risk effect of fetal gender on pregnant women at higher risk of preterm birth, and therefore its potential impact on targeting management. STUDY DESIGN: This was an analysis of prospectively collected data from a dedicated inner-city Prematurity Surveillance Clinic over a sixteen-year period. All women were high-risk for preterm delivery in view of their history, which included previous late miscarriage, PTB or significant cervical surgery. Obstetric variables and pregnancy outcomes were compared in male and female babies. Demographic and risk factors were compared between groups, and both spontaneous and iatrogenic preterm delivery rates interrogated (<24, <28, <34 and <37 weeks' gestation). Risk ratios (with 95% confidence intervals) were calculated for each gestational band. RESULTS: In this cohort, 14.5% of women (363/2505) delivered before 37 weeks. Pregnant women were stratified by fetal gender and were comparable for referral risk factors and demographic characteristics. There was no significant association between fetal gender and incidence of miscarriage less than 24 weeks (RR 1.17, 95% CI 0.65-2.10, p = 0.607), or preterm births 24 to 37 weeks RR 1.07 (95% CI 0.82-1.40, p = 0.383). Furthermore, analysis by gestational band [<28 RR 0.91 (95% CI 0.60-1.37, p = 0.647), <34 RR 1.18 (95% CI 0.89-1.57, p = 0.257 and <37 weeks RR 1.10 (95% CI 0.91-1.33, p = 0.309)] also showed no effect. This held true for both spontaneous and iatrogenic preterm delivery. In our high-risk cohort there was no gender difference for preeclampsia (RR 0.93, 95% CI 0.61 to 1.41, p = 0.725) or preterm premature rupture of membranes (PPROM) (RR 1.14, 95% CI 0.86 to 1.50, p = 0.384) CONCLUSIONS: In a high-risk cohort there was no significant increased risk of miscarriage, spontaneous or iatrogenic PTB, preeclampsia or PPROM for the male fetus. This is contradictory to low-risk populations and confirms that gender need not be integrated into high-risk management protocols for preterm birth.

The Actim Partus test to predict pre-term birth in asymptomatic high-risk women.

The Actim Partus test has been shown to be a useful predictor of pre-term birth in symptomatic women, but limited research has been carried out in high-risk asymptomatic women. This is a pilot study to evaluate the use of this test as a direct comparator with the fetal fibronectin test. All asymptomatic high-risk women attending a pre-term surveillance clinic over a 9-month period, took an Actim Partus and fetal fibronectin test, between 23(+0)-24(+6) weeks' gestation. A total of 45 women were eligible. The positive and negative predictive values of the Actim Partus test for delivery at ≤ 37 weeks' gestation were 0% and 70%, respectively, compared with the fetal fibronectin test, with values of 67% and 79%, respectively. It was concluded that the Actim Partus test did not perform well as a predictor of pre-term birth in high-risk asymptomatic women.

Low saliva progesterone concentrations are associated with spontaneous early preterm labour (before 34 weeks of gestation) in women at increased risk of preterm delivery.

Saliva progesterone and oestriol concentrations were determined weekly from 24 weeks of gestation in women at increased risk of preterm delivery. Samples were analysed from 28 women with spontaneous onset of labour and delivery before 37 weeks of gestation, and 64 who delivered at term. Saliva progesterone was lower in the 12 women delivering before 34 weeks than in those delivering later, between 34 and 37 weeks (P = 0.007) or at term (P = 0.009). Measurement of saliva progesterone may be of value in the prediction of early preterm labour and in determining which women might benefit from progesterone supplementation.

Fetal fibronectin as a predictor of spontaneous preterm labour in asymptomatic women with a cervical cerclage.

OBJECTIVE: To assess the accuracy of fetal fibronectin (fFN) testing for prediction of preterm labour in asymptomatic high-risk women with a cervical cerclage. DESIGN: Retrospective observational study. SETTING: United Kingdom. POPULATION: Nine hundred and ten asymptomatic women at high-risk of Preterm birth referred to specialist antenatal clinics and undergoing fFN testing between November 1997 and December 2007. METHODS: Women had fFN tests taken between 23(+0) and 27(+6) weeks' gestation, on one or more occasions. MAIN OUTCOME MEASURES: Sensitivity, specificity, positive predictive values and negative predictive values of fFN testing for predicting delivery <30 and <37 weeks were compared in those with and without cerclage. RESULTS: For delivery <30 weeks' gestation, the specificity of fFN testing was significantly lower in women with cervical cerclage (77% vs 90%; P < or = 0.00001). The sensitivity of the test was similar between the groups (78.6 (no-cerclage) vs 60% (cerclage); P > 0.4). The negative predictive value of the fFN test for delivery <30 weeks was high in both groups (>98%). CONCLUSIONS: Asymptomatic high-risk women with cerclage in situ are more likely to have a false positive fFN test. The negative predictive value is similar.