Population differences and the effect of vaginal progesterone on preterm birth in women with threatened preterm labor (.).

OBJECTIVE: Threatened preterm labor (tPTL) is a complication of pregnancy. Identification of women and clinical definition differs between countries. This study investigated differences in tPTL and effectiveness of vaginal progesterone to prevent preterm birth (PTB) between two countries. METHODS: Secondary analysis of a randomized controlled trial (RCT) from Argentina and Switzerland comparing vaginal progesterone to placebo in women with tPTL (n = 379). Cox proportional hazards analysis was performed to compare placebo groups of both countries and to compare progesterone to placebo within each country. We adjusted for baseline differences. Iatrogenic onset of labor or pregnancy beyond gestational age of interest was censored. RESULTS: Swiss and Argentinian women were different on baseline. Risks for delivery <14 days and PTB < 34 and < 37 weeks were increased in Argentina compared to Switzerland, HR 3.3 (95% CI 0.62-18), 54 (95% CI 5.1-569) and 3.1 (95% CI 1.1-8.4). In Switzerland, progesterone increased the risk for delivery <14 days [HR 4.4 (95% CI 1.3-15.7)] and PTB <37 weeks [HR 2.5 (95% CI 1.4-4.8)], in Argentina there was no such effect. CONCLUSION: In women with tPTL, the effect of progesterone may vary due to population differences. Differences in populations should be considered in multicenter RCTs.

The effect of migration background on obstetric performance in Switzerland.

OBJECTIVES: Population-based analysis to compare perinatal outcome between immigrant women and women from the Western industrialized world (WIW). METHODS: Singleton pregnancies of a cohort that was followed from the first trimester to delivery at the University Women's Hospital Basel, Switzerland, were retrospectively analysed. Data were extracted from 203 patient records. Multiple logistic and linear regression analyses were used to determine the impact of origin on perinatal outcome. RESULTS: Immigrants and women from WIW countries were comparable regarding number of pregnancy control visits. Immigrant women were younger, had more children, higher pre-pregnancy body mass index and were more often taking medication of any kind during pregnancy. Migration was only predictive for shorter gestations (p < 0.01). A trend for a lower frequency of gestational hypertension and labour inductions, and a higher frequency of spontaneous delivery and lower birth weights were observed. CONCLUSIONS: Migration background was associated with shorter gestations and lower birth weight. This was not due to differences in antenatal care since both study groups were followed at the same clinic with the same guidelines and had the same number of consultations during pregnancy. Higher stress levels due to migration and lower socioeconomic living standards, nutrition, and genetic factors are possible contributors to these findings.