Nifedipine-induced changes in body composition in hypertensive patients at term.

Background: There are few studies on the effect of nifedipine on fluid homeostasis during pregnancy.

Objective: To assess the variation of body composition at term in patients with normal pregnancy and patients with gestational hypertension (GH) treated with nifedipine.

Methods: Seventeen healthy patients with singleton pregnancies and 12 non-proteinuric patients with gestational hypertension treated with nifedipine were enrolled consecutively from our University Hospital from January 2000 to January 2001. Two evaluations were performed (anthropometric measurements, bioelectric impedance analysis (BIA) at 5, 50 and 100kHz and hematocrit), the first at 36.4+/-3.2 weeks' gestation, the second at 2.1+/-1.6 days of puerperium. The BIA measurements included: fat mass (FM, kg), fat-free mass (FFM, kg), extra-cellular water (ECW, Lt), intra-cellular water (ICW, Lt), total body water (TBW, Lt). Values were analyzed as mean+/-S.D. and statistical analysis was performed by using the Student's t-test for unpaired data.

Results: Birthweights were significantly lower in the gestational hypertensive patients (3472.7+/-266.4g versus 2735.8+/-575.9g, P<0.001). At the first study time, systolic and diastolic blood pressure were significantly higher in the hypertensive patients than in control group, notwithstanding the therapy. Interestingly we found pre-delivery and post-delivery TBW higher in gestational hypertensive patients versus the control patients (44.48+/-9.12Lt versus 36.60+/-5.07Lt, P<0.001 and 40.69+/-4.31Lt versus 37.30+/-4.35Lt, P=0.016, respectively). TBW loss after delivery was greater among hypertensive patients (3.79+/-4.81Lt versus -0.70+/-0.72Lt, P<0.001).

Conclusions: Bioelectrical impedance analysis is a practical tool in the follow-up of anti-hypertensive therapy at term gestation. Moreover, nifedipine increases TBW in gestational hypertensive patients, reverting the pathophisiological pattern, yet described elsewhere.