Pregnancy in patients with undifferentiated connective tissue disease: a prospective case-control study

OBJECTIVES: To assess the outcome of pregnancy and disease flare or differentiation into well-defined connective tissue disease (CTD), in a cohort of pregnant patients with undifferentiated connective tissue disease (UCTD) and to compare these findings with those obtained from a population of non-pregnant women with UCTD. METHODS: In total, 55 pregnancies (in 50 UCTD patients) were monitored from the positive pregnancy test until the sixth month after delivery. Likewise, during a 15-month timeframe, the incidence of flares or evolution into a major CTD was also recorded in a population of 53 non-pregnant women with UCTD. The Student t-test was applied for unpaired, continuous variables and chi-square was applied when percentages were compared. RESULTS: The mean duration of the successful pregnancies was 38.6 weeks (range 28-42) while the mean birth weight was 3190 g (range 1200-4600 g). Three pregnancies (5.4%) ended in miscarriage. The following obstetric complications were found: five premature membrane ruptures, two preeclampsia and two intra-uterine growth restrictions. In a total of 16 patients (32%) the disease flared during pregnancy or during the 6-month post-delivery period. Of these, five developed well-defined CTD after delivery. In the control population, six patients flared (11%) and, of these, only one developed a well-defined CTD. CONCLUSIONS: If pregnancy is properly treated, the outcome in UCTD patients is generally good while, considering disease activity, pregnancy appears to be a clear risk factor for flare up or evolution into well-defined CTD.