Question to the Department of Health and Social Care:

To ask the Secretary of State for Health and Social Care, what assessment he has made of the potential impact of exposure to Diethylstilbestrol on children of women who took that drug while pregnant.

The Medicine and Healthcare products Regulatory Agency continuously assesses the benefit and risk balance of all medicines, at the time of initial licensing and throughout their use in clinical practice, carefully evaluating any emerging evidence on their benefits and risks.

In 1971, it was recognised that diethylstilbestrol (DES) could cause a distinct type of cancer in the daughters of women who took DES in early pregnancy. Shortly afterwards its use was contraindicated in pregnancy, pre-menopausal women, children, and young adults, and the Committee on Safety of Medicines wrote to all doctors in May 1973 to advise against the use of DES in pregnant and pre-menopausal women.

A small increased risk of breast cancer in women who received DES whilst pregnant was first identified in the 1980s and confirmed in further studies in the 1990s, when a longer follow up of women who had taken DES was available. No increased risk of other cancers has been established, including endometrial cancer or ovarian cancer.

Since 1992, the National Cancer Institute at the US National Institutes of Health has been conducting the DES Follow-up Study of more than 21,000 mothers, daughters, and sons exposed in the womb during the mother’s pregnancy, to better understand the long-term health effects of exposure to DES. The findings of this follow up have been published in scientific literature.

Daughters of individuals exposed to DES are at increased risk of clear cell cancer of the cervix and vagina. The current advice from the UK Health Security Agency, formerly Public Health England, is that routine cervical screening is appropriate for those who believed they were exposed to DES in utero. Further information on the UK Health Security Agency’s advice is available at the following link:

https://www.gov.uk/government/publications/cervical-screening-programme-and-colposcopy-management/5-screening-and-management-of-immunosuppressed-individuals

Participation in the National Breast Screening Programme is also recommended. Pregnant women who know that they were exposed in utero to DES should inform their obstetrician and be aware of the increased risks of ectopic pregnancy and preterm labour.