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Obesity: A major challenge for modern obstetrics

We all want a healthy outcome for every pregnant mother and baby. But what if the mother-to-be isn’t as healthy as they could be? Obesity is one of the big challenges for modern obstetrics. Ideally, women should enter pregnancy with a normal body mass index (BMI), but the average pregnant mother is overweight and one-third are obese at the start of pregnancy.

This poses significant challenges for the mother and her baby, as well as to the healthcare professionals caring for her. Overweight and obese pregnancy is associated with increased complications for the mother, such as miscarriage, pre-eclampsia, gestational diabetes, Caesarean section, postpartum haemorrhage and venous thromboembolism. It is also associated with increased foetal complications, higher rates of foetal defects, growth restriction and large-for-gestational-age birth weight.

The Irish clinical guideline on obesity and pregnancy was published in 2011 and updated in 2013. It addresses the potential complications of obesity and pregnancy and strategies for caring for obese women during pregnancy.

Miscarriage

Twenty per cent of pregnancies that have not reached 12 weeks’ gestation end in miscarriage.  However, it is more common in obese women. Whether conception is spontaneous or assisted, the miscarriage rate remains higher in obese women. 

Folic acid supplementation should be taken by all women trying to conceive for three months prior to conception and during the first trimester of pregnancy. Consideration should be given to giving obese women the higher dose of 5mg folic acid supplementation. This will reduce the risk of neural tube defects such as spina bifida and anencephaly. In an Irish study, the rate of periconceptional folic acid supplementation decreased in the five years 2009-2013, particularly among women who were multiparous, aged 30-to-39 years, Irish-born, and obese.  Another study showed that this may be explained by the higher rates of unplanned pregnancy in obese women.

Recently, it has been highlighted that a 20-week anatomy scan should be available to all women attending Irish maternity hospitals. However, the current maternity services are understaffed and facilities and staffing levels do not enable all maternity units to provide this important service. An anatomy scan will detect about 70 per cent of structural abnormalities. It can, however, be technically challenging to visualise all the anatomy in obese women, as the ultrasound beam has to pass through layers of adipose tissue to visualise the baby.

Sometimes it may be necessary to repeat the scan at 24-to-28 weeks to obtain complete imaging and in some cases, clear views of the foetal anatomy may remain suboptimal.

Diabetes

In the Irish healthcare system, screening for gestational diabetes (GDM) is based on risk factors, including obesity. A glucose challenge test or glucose tolerance test is performed between 24 and 28 weeks’ gestation. For those women diagnosed with GDM, a multidisciplinary care approach to their pregnancy will include dietitian, endocrinology and obstetric reviews. For women with GDM, maintaining good glycaemic control can reduce the risks of foetal macrosomia, shoulder dystocia, third-degree tear and Caesarean section.

Obesity is considered a moderate risk factor for hypertension and pre-eclampsia in pregnancy. The recent MBRRACE (Mothers and Babies: Reducing Risk through Audits and Confidential Enquiries) report into maternal mortality and morbidity in the UK and Ireland focused on hypertension in pregnancy. While mortality from pre-eclampsia is reducing, there are still aspects of care that could be improved.

Women with risk factors for pre-eclampsia and those who develop hypertension or proteinuria in pregnancy should have a plan for an appropriate schedule of checks. Blood pressure and urinalysis should be checked at each antenatal attendance in both primary and secondary care and results of tests should be followed up. On a practical level, women with a mid-arm circumference (MAC) >33cm should have their blood pressure measured with a large cuff to avoid misdiagnosing pregnancy-induced hypertension or pre-eclampsia and avoid unnecessary interventions, such as induction of labour.

Caesarean section

The national Caesarean section rate has been steadily increasing and is now over 25 per cent. The reasons for this include increasing maternal age, medical comorbidities including obesity, and changes in obstetric practice, such as increasing rates of induction of labour and declining rate of vaginal birth after primary Caesarean section.

There is a two-fold increase in the risk of Caesarean section for obese women compared to those with a normal BMI. In primigravidas, there are higher rates of emergency Caesarean section for foetal distress and dystocia in labour. In multigravidas who are obese, especially those with a BMI >40, there is a low rate of trial of labour after Caesarean section. A Caesarean section can be technically challenging with central obesity and there is a high risk of wound infection. Strategies to reduce this include antibiotic prophylaxis and use of PICO dressings.

Women who are obese should also be advised to lose weight prior to pregnancy to improve fertility and reduce the risks of obesity in pregnancy

Thromboembolism

Venous thromboembolism remains the leading cause of direct maternal death in the developed world. Obesity is considered a risk factor for venous thromboembolism. Women should be risk-assessed for antenatal and postnatal thromboprophylaxis and given weight-appropriate doses when thromboprophylaxis is required.

Obese women should have an anaesthetic consultation before delivery, as they are at high risk of complications due to obesity and medical comorbidities.

Obese women have higher rates of failure of epidural insertion, difficulty with inserting peripheral venous access, failed intubation and higher risk of aspiration. Ultrasound has been successfully used in obese women to help identify the epidural space and reduce the need for general anaesthesia.

In women with a BMI ≥40kg/m2, consideration should be given to siting an epidural catheter early in labour to prevent a delay in case of an emergency Caesarean section.

Women who are obese should also be advised to lose weight prior to pregnancy to improve fertility and reduce the risks of obesity in pregnancy. For those who are obese at their booking visit, it is important to address the problem.

Pregnancy is an opportune time to promote a healthy lifestyle, including dietary and exercise advice. The Institute of Medicine recommends that obese women should gain a maximum of 5-to-9kg during pregnancy.

Exercises such as a brisk walk, swimming or pregnancy yoga are ideal for staying healthy throughout pregnancy. An observational study in a Dublin maternity hospital found that obese women were less likely to exercise in pregnancy compared to those with a normal BMI and that there was the potential to introduce an intervention for these women.

Trials

The ROLO study, a randomised, controlled trial of low glycaemic index diet in pregnancy, found that there was less gestational weight gain and less impaired glucose intolerance in pregnancy in the intervention group when compared to controls. Therefore, a healthy low glycaemic index diet is an effective and safe option for women who are overweight and obese and at risk of excessive gestational weight gain.

A randomised, controlled trial, the PEARS study, used a healthy lifestyle package for women with a BMI greater than or equal to 25kg/m2 to reduce the incidence of gestational diabetes. This lifestyle package included a motivational counselling session to encourage behaviour change, low glycaemic index nutritional advice and daily physical activity prescription delivered before 18 weeks’ gestation, as well as a smartphone app to provide ongoing health lifestyle advice and support throughout pregnancy. These multifaceted interventions hold considerable potential to improve maternal health during pregnancy.

Postpartum

Beyond pregnancy, what can we do? The six-week postpartum check is another opportunity to promote healthy living for the mother and her new baby. Again, keeping active and maintaining a healthy diet are important. Breastfeeding has health benefits for both mother and baby, including postpartum weight loss, reduction in breast cancer risk long-term and transfer of immunity from mother to baby.

What does the future hold?  Can we reduce obesity before the next pregnancy and improve pregnancy outcomes for Irish mothers? Public health campaigns and television shows such as Operation Transformation are helping us make a change as a nation. In the National Maternity Hospital, we have recently started a clinic for obese women who have had gestational diabetes in their last pregnancy.

Our aim is to see these women nine-to-12 months before they plan a future pregnancy and offer them lifestyle strategies, including pharmacological support such as liraglutide (a glucagon-like peptide analog) to lose weight and reduce their risk of gestational diabetes in their next pregnancy.

Increasing awareness among the public and healthcare professionals of the crucial importance of the perinatal period in influencing health outcomes for mother and baby is essential to ensure the next generation in Ireland achieves optimum health.

References on request 

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