Objectives This study examines pregnancy outcomes in Finland: gender differentiation, low birth weight, high birth weight, pre-term delivery and post-term delivery, small-for-gestational-age, large-for-gestational-age, stillbirth and early neonatal death for study occupations compared to controls

Method Among 507 659 prima gravida women were 12 854 hairdressers, 1841 cosmetologists and 3587 laboratory workers. The control populations consisted of 40 405 teachers, 1968 musicians and 447 004 women from the general population.

Adjusted odds ratios (aOR) were calculated using binomial logistic regression analysis. Adjustments made: maternal age, smoking habit, marital status, socioeconomic status.

Results aOR for male births was lower for hairdressers than teachers 0.92 (95% CI 0.87–0.98). aOR for post-term delivery was greater for cosmetologists compared to teachers, 2.13 (95% CI 1.04–4.35).

Crude odds ratios (ORs) were also statisitically significant Cosmetologists compared to musicians for ratio of male/female births, OR 1.04 (95% CI 1.00–1.08). Haidressers compared to the general public: small for gestational age, OR 1.01 (95% CI 1.00–1.02), large for gestational age, OR 1.02 (95% CI 1.00–1.03) and post term delivery OR 1.06 (95% CI 1.02–1.11).

The statisitically significant results for pooled effect size (ES) from the meta-analysis: low birth weight in hairdressers, ES 1.1 (95% CI 1.01–1.20) and small-for-gestational-age infants among hairdressers ES 1.18 (95% CI,1.08–1.30).

The pooled effect size for large for gestational age infants among hairdressers was statisitically significantly reduced for LGA infants among hairdressers, ES 0.71 (95% CI 0.55–0.91).

Conclusions Hairdressers, increased risk of certain pregnancy outcomes. Policy recommendations to improve protection forpregnant workers have been made.