Ontario physicians increased workload during the first two trimesters of pregnancy and reduced it in the third trimester, according to a population-based retrospective cohort study.
The overall increase was modest, but the pattern suggests physicians may shift work earlier in pregnancy in anticipation of leave.
The study, led by Andrea N. Simpson, MD, of the University of Toronto, and colleagues, analyzed 5,948 deliveries among 3,932 practicing physicians in Ontario, Canada, between 2002 and 2018, with follow-up through 2023.
Researchers used physician billing claims submitted to the Ontario Health Insurance Plan to measure work activity—defined as days worked and overnight billings—across pregnancy trimesters and a reference prepregnancy period defined as the same calendar window in the year prior to conception. Physicians were grouped into eight specialties: anesthesia or emergency medicine; diagnostic imaging; family medicine; medical specialties; obstetrics and gynecology (ObGyn); pediatrics; psychiatry; and surgery.
Workload Trends Across Trimesters
Compared with the prepregnancy reference period, overall workload increased slightly during pregnancy. Workload rose in the first and second trimesters and declined below prepregnancy levels in the third trimester. Nearly all specialty groups followed this pattern.
Exceptions included diagnostic imaging, medical specialties, and ObGyn, in which third-trimester workload returned to, rather than fell below, prepregnancy levels.
Overnight work showed a similar pattern but with a more pronounced decline in the third trimester. Overnight billing decreased overall, remained stable or slightly elevated in the first two trimesters, and dropped sharply in the third trimester. The largest decline occurred among physicians in anesthesia or emergency medicine.
Psychiatry was an outlier: overnight billing rates were higher across all three trimesters compared with prepregnancy—nearly threefold higher in the first and second trimesters—although absolute volume of overnight work remained lowest across all specialties. Overnight billing among physicians in diagnostic imaging remained largely unchanged.
Parental Leave and Return to Work
Return-to-work rates were high across all specialties during follow-up. Median time to return ranged from 133 days for surgery to 270 days for psychiatry, with ObGyn, diagnostic imaging, and medical specialties also among the earliest to return.
By comparison, fewer than 10% of Canadians receiving parental leave pay return to work before 8 months, with most returning between 9 and 12 months or later. The researchers suggested this gap likely reflects financial pressures and structural constraints within medical practice, rather than physician preference.
The median age at delivery was 35 years, and the median time from entering the workforce to conception was 3.6 years. First and second deliveries each accounted for 40% of the cohort, and family medicine represented nearly 59% of physicians.
Family Medicine Subgroup
Among family physicians, those in major primary care models—Family Health Network, Family Health Organization, Family Health Team, and Family Health Group—had higher return to work rates.
Median time to return ranged from 160 days to 199 days across these models. Physicians practicing outside these models had longer leaves (median, 228 days) and lower overall return-to-work rates during follow-up, highlighting potential differences in how practice structure supports parental leave.
Trends Over Time
The proportion of physicians returning to work within 180 days postpartum was lower in more recent years, suggesting slightly longer leave durations.
However, by 365 days postpartum, return-to-work rates were similar across time periods, indicating that physicians are not leaving the workforce at higher rates but are instead taking somewhat longer leaves.
Limitations
The study included only practicing physicians and could not capture resident leave patterns, as they do not submit billing claims. The researchers also could not evaluate leave practices among male physicians or among those who became parents through surrogacy or adoption, nor could they assess the influence of local practice policies or the COVID-19 pandemic.
Findings are specific to Ontario and may not generalize to other settings.
Context and Implications
The researchers suggested that increased workload in early pregnancy may reflect preparation for reduced income or clinical activity later in pregnancy, as well as perceived obligations to colleagues.
Financial support for practicing physicians in Ontario was limited, with a stipend of $1,000 per week for up to 17 weeks prior to 2025.
The researchers proposed that improving parental leave policies, increasing financial support, and expanding workforce flexibility—including adjustments to practice models and physician supply—could help address disparities in how medical practice accommodates childbearing.
“Ensuring adequate parental leave for physicians is a gender equity issue and should be addressed through workforce planning,” the researchers wrote.
Disclosures: Dr Simpson reported receiving funds from the St Michael’s Hospital Chair in Women’s Health and the University of Toronto Department of Obstetrics and Gynecology Merit Award. No other disclosures were reported. The study was supported by ICES and the Physicians’ Services Incorporated Foundation.
