Slow early β-hCG elevation is associated with increased risk for hypertensive pregnancy complications

Objective: To examine the association between rate of initial β-hCG rise following fresh in-vitro fertilization (IVF) cycles and long-term pregnancy complications. Methods: A cohort study including all patients undergoing fresh IVF cycles who had a single gestational sac on the first ultrasound and resulted in a singleton live birth. The elevation rate between the first β-hCG value taken at day 15 ± 1.4 after oocyte pick-up and second β-hCG value taken 2 ± 0.5 days later was assessed. A slow elevation was defined as doubling time above the 90th percentile of the study population. Results: Overall, 808 fresh IVF cycles qualified for inclusion in the study of whom 80 had a slow β-hCG elevation. There was no difference in baseline characteristics between the groups. The incidence of pregnancy induced hypertension was more than twice as high in the slow β-hCG elevation group compared to the normal β-hCG elevation group (14 % vs. 6 %, p 0.011). The adjusted risk ratio for this complication was 2.60 (95 % CI 1.26–5.33, p = 0.014) and remained significant after adjustment to maternal age, nulliparity and the first β-hCG value. Conclusion: Patients with slow β-hCG elevation in the fifth gestational week were approximately at a 2.6-fold higher risk for pregnancy induced hypertension complications when compared to patients with a normal β-hCG elevation. The early detection of this previously unrecognized risk group could allow tighter follow-up during pregnancy, which could potentially reduce these complications.