Re: Polycystic ovary syndrome and risk of stillbirth: a
nationwide register-based study a nationwide register-based study a
nationwide register-based study. BJOG. 2021 Aug 29
The aims of my letter are to comment on some of the methodological
aspects of your recent article on the association between polycystic
ovary syndrome and stillbirths1 and make an urgent
call for further research to validate the findings.
An important confounding variable that wasn’t addressed, was the authors
did not control for smoking which is a known risk factor for
stillbirths2. They argued that “Information on
the effect of smoking on PCOS is scarce in the literature, and therefore
smoking was not considered as a confounder ”. PCOS is however
associated with depression3 and depression is
associated with smoking4. Women with anovulatory
infertility were also classed as PCOS without objective verification and
a diagnosis of PCOS was not objectively excluded in the control group.
More studies are therefore urgently required to validate the findings in
the article and provide some insights into the possible mechanistic
links between PCOS and stillbirths. Ideally this would be a large
international prospective study with PCOS women properly diagnosed and
classified into the different phenotypes. However, the logistics of
organising a study like this might be a challenge. Other studies using
established cohorts of women with PCOS might address this challenge.
Some possible solutions include using women with PCOS recruited into the
UK Biobank or identified from the UK’s Clinical Practice Research
Datalink (CPRD). Although the use of these cohorts may also present some
similar challenges with phenotyping, present in the article published in
your journal, they might, offer the opportunity for independent
validation in cohorts of PCOS women of different demographics and
provide the opportunity to address some of the confounders not addressed
in the study published in your journal.
Best wishes
William Atiomo. MBBS, DM, MA, FRCOG, SFHEA.
Clinical Sub-dean, lead for international medical students and academic
head of undergraduate obstetrics and gynaecology. School of Medicine,
University of Nottingham. UK