Is ambulatory blood pressure monitoring predictive of outcome when taking place at the 4th month of pregnancy in a normotensive primigravid population? Results from a multicenter French study: about 170 cases

Objective: to evaluate in a primigravid normotensive population the predict ive value of outcome of the ambulatory blood pressure monitoring (ABPM) at the 4th month of pregnancy. Design and Methods: a longitudinal observational study was carried out in 1 74 primigravid normotenvives free from proteinuria and glycosuria during th e first trimester. These women underwent an ABPM (Spacelabs 90207) at 17 +/ - 3 weeks gestation and were then followed up throughout pregnancy for the identification of outcome : gestational hypertension (blood pressure greate r than or equal to 140/80), proteinuria, hyperuricemia, preterm delivery, b irth weight < 10th percentile, need for admission to the special care neona tal unit (SCNU). Statistics: non parametric tests, ROC curves. Results: of the 174 women, 170 had sufficient readings to be considered for analysis, Pre-eclampsia occurred in 5 cases (3%), gestational hypertension in 27 (16%), proteinuria in 20 (12%), hyperuricemia in 2 (1%), preterm del ivery in 11 (6%), low birth weight in 9 (5%) and admission to SCNU in 16 (9 %). Women with gestational hypertension already exhibited at the 4th month, both ambulatory and clinical blood pressure (BP) higher than did normotens ive women (respectively : 117 +/- 7 / 70 +/- 5 vs 110 +/- 7/65 +/- 6 mmHg, p < 0.0001 for 24-hour ABPM, and 124 +/- 8/76 +/- 7 vs 117 +/- 10 / 70 +/- 9 mmHg, p < 0.005 for clinical BP). There was a non significative trend for both ambulatory and clinical values to be slightly higher in the setting o f preterm delivery, proteinuria and admission to SCNU and in contrast to be slightly lower in case of low birth weight. The occurrence of one outcome or more (49 outcomes, low birth weight excepted), was associated with signi ficantly higher ambulatory and clinical BP levels (114 +/- 7 / 68 +/- 6 vs 111 +/- 7/65 +/- 5 mmHg, p < 0.009 for ABPM, and 121 +/- 9/74 +/- 8 vs 117 +/- 9/70 +/- 8 mmHg, p < 0.007 for clinical BP). Positive and negative pred ictive values for the outcome of gestational hypertension were respectively for systolic ambulatory BP of 28% and 95% using a cut off value of 115mmHg and for systolic clinical BP of 26% and 97% using a cut-off Value of 120 m mHg. Conclusion: ABPM in a normotensive primigravid population at 17 weeks of ge station is not a better predictor of outcome, even of gestational hypertens ion, than clinical measurement.