Medications used during fertility treatment may pose risk of birth defects

Women in fertility treatment are more likely to take medication that could harm a fetus before or during pregnancy, according to a study of over 57,000 births in Australia.

Researchers from South and Western Australia analysed pregnancies by fertility treatment type to assess exposure to teratogenic medications — drugs that can cause birth defects. Their findings revealed that women using Assisted Reproductive Technology (ART), including IVF and ICSI, or ovulation induction (OI) were more frequently prescribed these medications compared to those conceiving naturally.

'These differences in exposure are primarily linked to medications used as additional treatment following ART to prevent repeat miscarriages or failed implantation, rather than medications to treat underlying chronic conditions,' said lead author Dr Anna Kemp-Casey from the University of South Australia.

Published in the Australian and New Zealand Journal of Obstetrics and Gynaecology, the study examined medicine use before and during pregnancy for 57,681 births from conception after 1 July 2012 to delivery no later than 31 December 2014. It found nearly eight percent of women were dispensed teratogenic medications a year before conception, with less than one percent exposed during pregnancy.

The study examined exposure in all three trimesters to more than 200 medicines classified by Australia's Therapeutic Goods Administration as categories D and X. Category X medications carry a high risk of fetal harm and should be avoided, while those of category D may pose risks depending on pregnancy stage and maternal medical need (such as use of antidepressants, hypertensives or anti-epileptics).

The team compared the exposure among four groups: ART pregnancies, OI pregnancies, women who experienced difficulties conceiving (subfertile) but conceived without treatment; and naturally-conceived pregnancies (fertile). For D medicines, exposure in the first trimester was highest among women in the ART group (almost five percent), and the OI group (two percent), compared to just one percent or less in pregnancies from the subfertile or fertile groups. This trend was maintained in the last semester.

Progestagens and immunomodulators were the medicines to which pregnancies from ART and OI were most exposed. Progestagens have similar effects to the hormone progesterone, required to support pregnancy. The study noted that exposure to category X drugs was minimal across all groups, at less than half a percent.

'For example, ART pregnancies, during the study period were more often exposed to progestogens like medroxyprogesterone acetate, which may have been used to treat threatened or recurrent miscarriages,' Dr Kemp-Casey said.

The authors suggested further research to explore whether birth defects associated with these drugs occur more frequently in ART or OI pregnancies.

The study concluded that given the significant exposure of Australian women to medication that poses a risk to the fetus, a review of prescribed medicines should be offered to all women planning pregnancies.