Amniocentesis in the second trimester and congenital talipes equinovarus in the offspring: a population-based record...

To investigate whether amniocentesis in the second trimester is associated with congenital talipes equinovarus (CTEV) in the offspring.

Case-control study nested within a population-based cohort, developed through linkage of the Scottish Congenital Anomalies Linked Database with records of amniocentesis from cytogenetics laboratories, including 564,299 singleton births 1992-2001. Odds ratios and 95% confidence intervals for CTEV in the offspring (isolated, non-isolated, total) were calculated using logistic regression, adjusting for maternal age, year of birth and health board of birth.

There was a modest positive association between total CTEV and amniocentesis at any time (OR = 1.27, 95% CI 0.99-1.65) and at >or= 15 weeks (OR = 1.25, 95%CI 0.95-1.64). The association was strongest for non-isolated CTEV (amniocentesis any time: OR = 1.68, 95%CI 1.08-2.61; amniocentesis >or= 15 weeks: OR = 1.81, 95%CI 1.16-2.83). Amniocentesis at >or= 20 weeks was associated with increased risk of total (OR = 5.87, 95% CI 3.38-10.21), non-isolated (OR = 13.17, 95% CI 6.49-26.74) and isolated CTEV (OR = 3.10, 95% CI 1.28-7.49). There were no associations in mothers aged >or= 35 years.

The modest association observed is most likely accounted for by amniocenteses conducted because of an earlier abnormal prenatal test. Thus, second trimester amniocentesis is unlikely to contribute to the development of CTEV in the offspring.