UBC Study on 500,000+ BC Births Links Sequential Vacuum-Forceps to Higher ADHD Risk

Groundbreaking UBC-Led Study Examines Birth Methods and Child Neurodevelopment

A major new study led by researchers from the University of British Columbia (UBC) and McMaster University has analyzed over 500,000 births in British Columbia, shedding light on the long-term neurodevelopmental outcomes associated with different delivery methods during the second stage of labor. Published in JAMA Network Open on January 30, 2026, the research compares forceps, vacuum extraction, sequential instrumental delivery (vacuum followed by forceps), and second-stage cesarean delivery (SSCD). The findings offer reassurance for parents and clinicians while highlighting subtle risks linked to certain techniques, particularly for attention-deficit/hyperactivity disorder (ADHD).

This population-based cohort investigation draws from comprehensive health administrative data, providing one of the largest and most robust datasets on this topic. By focusing exclusively on second-stage interventions—clinically comparable options when spontaneous vaginal delivery isn't feasible—the study addresses longstanding gaps in prior research that often pitted operative births against uncomplicated vaginal ones.

Defining Instrumental Birthing Techniques: Vacuum, Forceps, and Beyond

Instrumental birthing techniques, also known as operative vaginal deliveries, assist in expediting birth during the second stage of labor, when the baby is descending through the birth canal but progress stalls. Vacuum extraction uses a soft cup attached to the baby's head via suction, pulled gently with contractions. Forceps involve two spoon-shaped metal instruments placed around the baby's head to guide it out.

Sequential instrumental delivery occurs when vacuum fails, prompting a switch to forceps—a rarer but more complex scenario comprising just 0.6% of cases in the study. Second-stage cesarean delivery (SSCD) involves surgical extraction after labor has advanced significantly, often chosen when instrumental methods pose risks. These approaches, while life-saving in emergencies like fetal distress, have declined in Canada amid rising cesarean rates, from around 12% instrumental deliveries in the early 2000s to lower figures today, per perinatal trends.

The Methodology: Analyzing Half a Million BC Births

Researchers utilized the British Columbia Perinatal Data Registry, linked to hospitalization, outpatient, prescription, and vital statistics databases, covering 834,669 births from April 2000 to December 2019. After exclusions for preterm/post-term gestations, breech presentations, anomalies, and early infant deaths/emigration, 504,380 full-term singleton infants remained.

Follow-up extended to March 2022 (up to 22 years), tracking diagnoses of ADHD, autism spectrum disorder (ASD), and intellectual disability (ID) via validated ICD codes and medication records. Cox proportional hazards models adjusted for confounders like maternal age, BMI, smoking, diabetes, parity, infant sex, birth weight, fetal distress, and dystocia. Delivery modes: 80.9% spontaneous vaginal (descriptive only), 9.2% vacuum, 4.6% forceps, 0.6% sequential, 4.7% SSCD.

Key Findings: Modest Risks for Specific Techniques

Overall neurodevelopmental rates were low: ADHD at 6.6 per 1,000 person-years, ASD at 1.8, ID at 0.3. Compared to SSCD:

• Vacuum: No ADHD/ASD difference; 53% higher ID risk (aHR 1.53, 95% CI 1.12-2.10; 0.3 vs 0.2 per 1,000 person-years).
• Forceps: Similar across all outcomes (ADHD aHR 0.99, ID aHR 1.33 non-significant).
• Sequential instrument: 13% higher ADHD risk (aHR 1.13, 95% CI 1.00-1.28; 7.9 vs 6.6 per 1,000 person-years); no ASD/ID difference.

Cumulative incidence curves confirmed divergence by age 10-15 years. Absolute risks remain small, but findings underscore sequential vacuum-forceps as riskier.

Detailed Hazard Ratios and Cumulative Incidence Insights

*Significant (P<0.05). Sensitivity analyses (imputation, no smoking adjustment) confirmed robustness. Figures showed ADHD curves separating for sequential by adolescence.

Context from Prior Research and Trends

Prior studies often confounded comparisons (e.g., operative vs spontaneous vaginal). This UBC-McMaster work isolates second-stage choices. Earlier UBC research (e.g., Lisonkova et al.) highlighted maternal/neonatal trauma in forceps/vacuum (25% severe perineal tears in forceps), contributing to Canada's instrumental decline (from 11-12% to ~7-8% recently). ADHD affects 5-7% Canadian children; etiology multifactorial (genetics 70-80%, environment). No prior large cohorts linked specific instruments to ADHD/ID precisely.

Researcher Perspectives: Reassurance with Caution

Senior author Giulia Muraca (McMaster/UBC affiliate): "Multiple delivery options can be used without compromising long-term child development when intervention is needed." Maya Rajasingham emphasized small absolute risks. Experts like Alison Edlow (Harvard) note practitioner training influences choice; MedPage reports clinicians weigh fetal distress urgency.

Sarka Lisonkova (UBC SPPH perinatal epidemiologist) contributes extensively to maternal-fetal outcomes, bolstering Canada's perinatal data expertise.

Implications for Canadian Obstetrics and Policy

With C-sections at ~30%, instrumental ~7-10%, findings support informed consent emphasizing second-stage risks. SOGC may refine guidelines; training simulation urged to reduce sequential failures. Public health: ADHD diagnosis up 1.4-fold in Ontario (to ~8%); modifiable perinatal factors key.

Guidance for Expectant Parents in Canada

• Discuss birth plans early; know hospital capabilities.
• Fetal monitoring detects distress promptly.
• SSCD viable if instruments fail.
• Post-birth: Monitor development; early ADHD intervention effective.

Consult Canadian academic resources for university-linked clinics.

UBC and McMaster's Leadership in Perinatal Epidemiology

UBC's School of Population and Public Health (SPPH) pioneers BC Perinatal Data Registry analyses, training epidemiologists via MSc/PhD programs. McMaster's HEI complements with evidence synthesis. Link to higher ed jobs in public health.

Future Research and Evolving Practices

Ongoing: Sibling studies control genetics; neuroimaging links trauma to neurodevelopment. Declining instruments (due to trauma concerns) vs C-section risks balanced. Global collaborations via CIHR enhance datasets.

Photo by Izabelly Marques on Unsplash

Public Health Outlook: Balancing Risks in Modern Birthing

This UBC study reinforces evidence-based obstetrics, aiding Canada's 350,000+ annual births. For academics, highlights big data's perinatal power. Explore professor ratings, jobs, career advice.