Lower birth rate in patients with total hip replacement – A nationwide population-based study in Finland

Background and purpose — There have been few studies on the effect of THR on pregnancy or delivery, and they have mainly been based on small and regional data. We evaluated the birth rate nationwide in patients of fertile age with THR.

Patients and methods — This nationwide population-based cohort study was based on registry data on 5,863 Finnish THR patients who had undergone a THR between 1985 and 2006, and who were aged 15–45 years (females) or 15–50 years (males) at the time of THR. The matched reference cohort consisted of 17,575 sex- and age-matched individuals (3 for each patient) who were alive and resident in Finland at the time of the patient’s THR. Birth rate and Cox hazard ratios (HRs) with 95% CI for live births were calculated.

Results — The birth rate after THR was approximately 20–60% lower in the male and female patient groups than in the reference individuals. The probability of having a live birth after THR was lower in female patients than in reference individuals, in all but the oldest age group (40–45 years). The same phenomenon was seen in male patients in all but the youngest age group (15–19 years). Adjustment for potential confounders increased the probability of THR patients having a live birth compared to reference individuals, but the birth rate was still clearly reduced (in men, adjusted HR =0.80, 95% CI: 0.69–0.92; in women, adjusted HR =0.56, 95% CI: 0.46–0.68).

Interpretation — THR has a substantial effect on the birth rate of offspring, in both women and men. THR patients had a lower birth rate and probability of having a child after surgery, even after taking possible confounders into account.