Congenital anomalies in the offspring of women with total hip replacement: a nationwide register study in Finland

Abstract

Background: Few previous studies have analysed the possible teratogenic effect of maternal total hip replacement (THR) on congenital anomalies. The aim of this study was to estimate the risk of major congenital anomalies in the offspring of women with THR. Furthermore, we compared the risks based on type of implant (metal-on-metal [MoM]/non-MoM). Methods: The study population for this register-based cohort study was gathered from six Finnish national registers. All fertile-aged females who underwent THR from 1980 to 2007 and three reference females for each THR patient without THR were selected. THR operation day was the start of the follow-up for both groups. Information on pregnancies, induced abortions (IA) and congenital anomalies was gathered for the years 1987–2007 and the proportions of congenital anomalies were compared. Results: In the THR group, 2429 women had 256 pregnancies, 205 (80.1%) deliveries and 51 (19.9%) IAs. In the reference group, 7276 women had 1670 pregnancies, 1443 (86.4%) deliveries and 236 (13.6%) IAs. There was no difference in the incidence of major anomalies between the THR (3.5%, n = 9) and the reference group (3.6%, n = 60), p = 0.91. In the THR group, there was no difference in the risk of major anomalies between the patients with a MoM-THR (10.5%, 2/19) and those with a non-MoM (2.9%, 7/241) (OR 3.93, 95% confidence interval 0.76–20.2; p = 0.13). Conclusions: Reassuringly, maternal THR does not appear to increase the risk of major congenital anomalies or pregnancies ending due to suspected foetal anomalies. Studies with larger study populations are needed to further assess the risk of anomalies in the offspring of women having MoM-THR.