Benefits of a healthy weight before pregnancy cannot be overemphasised
It is crucial that women considering pregnancy first look after their own health
A woman increases her chances of pregnancy by being a normal weight. Photograph: Thinkstock
Achieving a healthy weight is the most effective intervention any overweight or obese woman can make to help her to become pregnant. It also increases her chances of having a healthy pregnancy and, moreover, a healthy baby.
Weight loss is often a difficult challenge. Doctors and midwives are sensitive to this and actively encourage and support women in this process.
Medical advice and terminology is often based on the woman’s BMI (body mass index), which can be difficult to relate to in the real world. The average Irish woman’s height is 5ft 4in. A healthy weight for a woman of this height is between 7st 12lbs and 10st 3lbs. If she weighs more than 12st 8lbs, her BMI is greater than 30 and she is classified as obese.
Weightloss regularises periods and increases the chance of spontaneous ovulation and conception in overweight and obese women.
Difficulties in conceiving naturally mean many couples are referred for assisted reproduction techniques such as IVF (in vitro fertilisation), but its success rates are reduced in obese women, who respond poorly to induction of ovulation with medication such as clomiphene.
Ovarian stimulation for assisted reproduction produces fewer follicles, resulting in the harvest of fewer oocytes (eggs). Even if an obese woman successfully produces oocytes, her chances of fertilisation are decreased and the embryo quality is poorer, with a higher rate of miscarriage.
Risks to baby
Therefore, women with a BMI greater than 29 should take a higher dose folic acid (5mg) for at least one month prior to conception, and continue to do so throughout the first trimester.
Vitamin D levels are frequently low in obese people, therefore women are encouraged to take supplements (10 micrograms per day) during pregnancy and breastfeeding. This is important for foetal bone and skeletal development, and may help to prevent chronic illnesses later in the baby’s life.
Having a higher BMI increases the risk of having a baby with an abnormal weight, so obese women have an increased chance of having a dangerously small or a dangerously big baby.
The size of the baby is difficult to estimate in obese women. The mother’s fatty tissue can prevent the doctor measuring the baby accurately and even prevent ultrasound scanning measuring appropriately.
These bigger babies have a risk of shoulder dystocia, which is an emergency situation at the time of delivery that can result in nerve damage or sometimes the death of the baby.
Risks to mother
A raised BMI doubles a woman’s risk of developing pre-eclampsia, which is a condition associated with high blood pressure and protein in the urine. It can impair the ability of the placenta to supply nutrients to the growing baby. Untreated, pre-eclampsia can lead to seizures, which are life-threatening to both mother and baby.
Obese women are two to three times more likely to require a Caesarean section and it is often a more complicated procedure. An obese woman is also at increased risk of haemorrhage, thus needing a blood transfusion.
The more overweight the woman is, the more likely she is to have a wound infection after her Caesarean section. Obesity also decreases a woman’s chance of having a vaginal delivery after a Caesarean section.
Delivery is often complicated in obese women. It is advised that obese women have an epidural during labour, but the volume of fatty tissue overlying their backs can make it difficult to place the epidural.
Even procedures as simple and essential as placing a cannula or “drip” can be challenging in obese women, causing distress for both patient and healthcare professional.
Rotunda strategiesRotunda Hospital
Several strategies have been implemented in the hospital to improve the health of the obese mother and her baby. Due to the high numbers of obese patients, dietitian Laura Harrington can see only those with the highest BMIs in her clinic.
Unfortunately, by the time they reach her service, it is often too late to reverse the problem of their obesity. She advises that weight gain begins only after 12 weeks of pregnancy.
Women who are obese should aim to increase their weight by between 11lbs and 19lbs by full term.
These women are given an information pack with dietary and exercise advice and sample dietary plans. A family effort to promote lifelong healthy eating is advocated.
Gestational diabetes is diabetes that develops during pregnancy. About 40 per cent of mothers who develop this condition are obese. Interestingly, another 40 per cent are not obese, but they have a family history of diabetes, including a family history of gestational diabetes.
Children born to obese women have an increased risk of obesity themselves. Furthermore, children whose mothers had gestational diabetes are at increased risk of developing diabetes in later life. The key message for these women is to lose weight before their next pregnancy.
This should be done with the help of her GP and community dietitian, who may prescribe a combination of exercise and dietary changes.
Achieving a healthy weight is something every young woman considering motherhood can do to benefit herself and her child. The benefits of this will last far longer than the duration of the pregnancy. It will ensure the best possible chances of having a happy, healthy baby.
Dr Tara Feeley is a specialist trainee in anaesthesia at the Rotunda Hospital in Dublin. Dr Kate Glennon is a registrar in obstetrics and gynaecology at the Rotunda.