PCOS (PMOS) and pregnancy: risks, screening and care

The NHS describes PMOS as a hormone condition that can affect hair growth, periods, fertility and mood, with symptoms such as irregular periods, excess hair, acne and difficulty getting pregnant. It explains that it can sometimes cause problems getting pregnant because the ovaries do not release an egg each month. The RCOG notes that you may still become pregnant even without periods, and recommends contraception advice if pregnancy is not wanted.

Treatments listed by the NHS for fertility include clomifene, a medicine to improve ovulation, and, where other measures have not worked, laparoscopic ovarian drilling, which uses heat or laser to treat ovarian tissue. Metformin is also listed for some PMOS symptoms. Whether to use or continue any medicine around conception is a specialist decision, so tell your GP or fertility clinic that you are planning pregnancy.

A systematic review and meta-analysis in Nature Communications pooled 104 studies and found that women with PCOS were younger, had a higher body mass index around conception and gained more weight in pregnancy. They had higher odds of miscarriage (about 1.5 times), gestational diabetes, gestational hypertension, pre-eclampsia (about 2.3 times) and caesarean section. Higher odds of miscarriage, gestational diabetes, hypertension, pre-eclampsia and caesarean birth remained after matching for age and BMI and in higher-quality studies.

These are odds from observational data with considerable variation between studies, not a forecast for any one person. The authors note that the added risk appeared worse with older age, higher BMI and assisted conception, and that more data are needed on outcomes such as perinatal depression.

NICE guidance on antenatal care expects midwives to assess risk factors for pre-eclampsia at booking and again in the second trimester, to measure blood pressure at every routine appointment and, for those at risk, to advise on aspirin as set out in the hypertension in pregnancy guideline. PCOS is not itself named in NICE's lists of high or moderate risk factors for aspirin, which include chronic kidney disease, diabetes, chronic hypertension, age 40 or over and a body mass index of 35 or more, so the decision depends on the whole picture.

The RCOG leaflet on PCOS states that because gestational diabetes is more common you will be offered a blood test between 24 and 28 weeks. Your midwife may also offer advice about healthy eating and activity in pregnancy, with the aim of supporting steady weight gain.

• Blood pressure and urine checks at each antenatal visit.

• A glucose test, usually between 24 and 28 weeks.

• Growth scans if there are concerns about the baby's size.

• A discussion about birth options, including the higher caesarean rate seen in studies.

NICE advises seeing a healthcare professional immediately for symptoms of pre-eclampsia: severe headache, problems with vision such as blurring or flashing before the eyes, severe pain just below the ribs, vomiting, or sudden swelling of the face, hands or feet. Vaginal bleeding or reduced baby movements also need same-day contact with the maternity unit or NHS 111, and 999 is for fits, collapse or heavy bleeding.

The RCOG explains that PCOS is associated with insulin resistance and with higher chances of developing type 2 diabetes, heart disease and other conditions later in life, and that healthy eating, regular exercise and a normal body weight reduce those risks.

The NHS also lists depression and anxiety among problems linked to PMOS, so mood changes during or after pregnancy should be raised with a midwife, health visitor or GP. Contraception choices after birth should be discussed with a midwife or GP.