Fractures and Orthopaedic Disorders During Pregnancy and the Following Recovery Period: An epidemiologic nationwide register study

Mothers experience various physiological changes both during pregnancy analyse the incidence of common orthopaedic disorders during pregnancy and the first year after delivery. We collected data on orthopaedic trauma and operations for all women aged 15 to 49 years as well as on all pregnancies in Finland over a 21-year period from 1 January 1998 to 31 December 2018. We created age-adjusted cohorts of orthopaedic disorders mortality were studied separately. Similar data for fractures occurring and the postpartum period that make them more vulnerable to the orthopaedic disorders caused by altered bone, connective tissue and hormonal metabolism. Since these conditions have significant effects on both the mother and the developing foetus, they require special attention. Although there have been several case reports and series on the epidemiology of orthopaedic disorders during pregnancy, no large-scale studies have been conducted thus far.

To fill this knowledge gap, we carried out a retrospective cohort study based on data from two Finnish national registries. The study aimed to
occurring during pregnancy or the first postpartum year, and outside of these periods. We used logistic regression models and Kaplan-Meier survival analysis for statistical analysis and included data on maternal smoking as a risk factor for events.

In study I, we analysed the incidence of fracture hospitalisation and fracture surgery during pregnancy. Pelvic trauma and rates of perinatal

during the first postpartum year were analysed in study II. Traumatic ruptures of the pubic symphysis occurring after vaginal delivery were analysed separately in study III. In study IV, we analysed the incidence of lumbar discectomy during pregnancy and the first postpartum year. Similar incidences regarding peripheral nerve decompression surgery were analysed separately in study V.

The main findings of our study were that the incidence of fractures during pregnancy (study I) was lower than in the normal female population of the same age (IRR 0.34, CI 0.33 to 0.34). The total fracture incidence was 247 fractures per 100 000 pregnancy-years (95% CI 237 to 259) leading to hospitalisation during pregnancy. Of these, about one fifth required operative treatment resulting in an incidence of 61 operations per 100 000 pregnancy-years (CI 56 to 67). After delivery (study II), the total incidence of fractures leading to hospitalisation during the first 12 months after delivery was 280 fractures per 100 000 person-years (95% CI 270 to 290) with one fourth of these fractures requiring operative treatment. Incidences of pelvic fractures during the first 4 months postpartum were similar to those in the normal population, but otherwise all rates remained lower. Traumatic ruptures of the pubic symphysis following vaginal birth (study III) occurred at a rate of 0.8 ruptures per 100 000 deliveries (CI 0.4 to 1.5).

For lumbar discectomy (study IV), the cumulative incidence during pregnancy was 11 operations per 100 000 person-years and 47 operations per 100 000 person-years during the first postpartum year. For pregnant women, the immediate reoperation rate was lower than the normal population with an IRR of 0.5 (CI 0.1 to 3.5), but higher during the first 12 months after pregnancy with an IRR of 1.7 (CI 1.1 to 2.7). Maternal smoking before pregnancy increased the risk of lumbar discectomy during pregnancy.

For peripheral nerve decompression surgery (study V) the most common procedure was carpal tunnel release (CTR), as only isolated cases of other operations were performed. The total incidence of CTR during pregnancy was lower than in the normal population with 38 operated women per 100 000 person-years (IRR 0.5, CI 0.4 to 0.6). After delivery, the incidence rose to 63 operated women per 100 000 person-years in the first postpartum year (IRR 0.8, CI 0.7 to 1.0). The risk of CTR during and after pregnancy was higher for women who actively smoked before pregnancy.

According to the results of our study, pregnant women sustain fewer fractures on a nationwide level when compared to similar aged women in the normal population. This phenomenon continues until at least the end of the first postpartum year. Despite this, the share of operative treatment for fractures is similar to that of the normal population. Interestingly, women are less likely to undergo lumbar discectomy and CTR, especially during pregnancy. One possible explanation for this is that surgeons may be more hesitant to perform operations during pregnancy due to concerns about the safety of the foetus.