Validity in Nulliparas of Increased b-Human Chorionic Gonadotrophin at Mid-Term for Predicting Pregnancy-Induced Hypertension Complicated with Proteinuria and Intrauterine Growth Retardation
The objective of the present study was to investigate whether increased β-human chorionic gonadotrophin (βHCG) plasma concentrations in an unselected population of nulliparas could predict the occurrence of complicated pregnancy-induced hypertension (PIH). The design was that of a prospective population study. It was conducted at the obstetric departments of Amiens University Hospital and Creil General Hospital on 434 consecutive nulliparas with singleton pregnancies after natural fertilization who accepted the systematic offer of trisomy 21 screening but for whom this disorder was finally eliminated. Measurement of plasma concentration of βHCG (ELISA method) was carried out between 14 and 20 weeks (mean: 17 weeks) of amenorrhea, and measurement of blood pressure and proteinuria ( > 300 mg/24 h or Albustix ++) during the first, second and third term and 2-3 months after the delivery, as well as measurement of birth weight for determination of small for gestational age (SGA) babies. 37 women developed PIH, 10 without other complication, 16 with proteinuria (5 of which with SGA babies) and 11 with SGA babies. Furthermore 2 patients presented abruptio placentae without PIH. 395 women did not develop PIH including 389 normotensive women and 6 chronic hypertensive patients without superimposed toxemia. Only 1 was diabetic. None had chronic renal disease. Mean ( ± SD) levels of βHCG were higher in PIH than in controls: 46,805 ± 19,068 versus 23,479 ± 13,463 IU. A pathological threshold was chosen as the mean for the whole population + 1 SD: 25,613 + 15,479 = 41,082 IU. Elevated levels (above this value) were significantly associated with isolated PIH or PIH complicated with proteinuria and/or with SGA babies. The positive predictive value of this criterion was respectively 11, 15 and 12% for each of these complications. The relative risk (and 95% confidence limit) of women with elevated βHCG for each of these complications was 20 (6-79), 11 (4-43) and 22 (7-93). Elevated plasma βHCG found around 17 weeks of amenorrhea predicts PIH complicated with either proteinuria or SGA babies with a positive predictive value comparable to that of the best and earliest test proposed up to now to select nulliparas at high risk of preeclampsia, namely the abnormalities of the Doppler waveforms of the uterine arteries. Since this test is simpler to perform, it represents the most convenient method to screen a population of nulliparas for evaluation of the benefits of low-dose aspirin.