Obesity is a chronic condition arising due to an excess amount of body fat. It is global issue that is becoming more and more prevalent. WHO suggests that approximately 13% of adults worldwide are obese. Obesity is less prevalent in many African and Southeast Asian countries and is highest in Europe and the Americas. In England, 26% of adults were classified as obese.
🔍 How do we calculate if someone is obese?
There are many ways to diagnose obesity, but the most common way is to use their Body Mass Index (BMI). It is a reasonable measure in the majority of people, but has drawbacks in pregnant women or in individuals with a large amount of muscle mass.
When planning pregnancy while obese, it is advised to lose weight.
Losing weight has multiple benefits to women who are planning to get pregnant:
- Reduces the risk and prevalence of fertility problems. The same is true for men.
- Reduces risks of complications during pregnancy (maternal as well as foetal risks). We will discuss these risks later.
- To be eligible for NHS funded IVF treatment, the woman must have a BMI between 19-25 for at least 6 months.
- Women should be referred to weight-loss support programmes that help with both diet and physical activity.
- 💊 Obese women should take 5mg folic acid as opposed to the typical 400mcg that is recommended to women who are trying to conceive. It should be taken for one month prior to conception until the 13th week of pregnancy.
Having a high BMI in pregnancy poses some risks both maternally and foetally. For this reason if a lady’s BMI is >30 at the booking appointment, they may be offered a consultant-led care package.
🚨 Complications
Antepartum complications
- Venous thromboembolism
- Gestational diabetes
- Pregnancy induced hypertension and pre-eclampsia
- >40 years old
- History of pre-eclampsia
- Diagnosis of hypertension prior to pregnancy
- Mental health issues
- Miscarriage - the risk of miscarriage in obese women increases from 20% to 25%.
- Neural tube defects
- Macrosomia
- Stillbirth
- Increased risk of obesity and diabetes in childhood
Obesity increases the risk of VTE even further. Pregnancy itself is a hypercoagulable state. Therefore a mother might be offered a low molecular weight heparin (LMWH) such as enoxaparin during pregnancy to reduce this risk of thrombosis. LMWHs are safe during pregnancy.
Obesity carries a 3x greater risk for developing gestational diabetes. Obese women will be offered an oral glucose tolerance test (OGTT) at 24-28 weeks of gestation.
The risk of pre-eclampsia is 2-4x higher in obese women. Blood pressure and urine dipsticks should be monitored throughout all appointments during pregnancy.
💊 Practitioners may recommend low dose aspirin if there are the following concomitant risk factors:
There is a slight increased risk of mental health issues that occurs with pregnancy and this risk further increases with overweight and obese patients. Pregnant women should be screened for depression using the Patient Health Questionnaire-2 (PHQ-2) score.
There are some risks posed to the foetus as well:
Intrapartum complications
- Preterm birth
- Prolonged labour
- Emergency C-section
- Anaesthetic complications
- Postpartum haemorrhage
If the mother’s BMI is >40 there is an increased risk of preterm birth (<37 weeks of pregnancy).
With obese patients, an epidural may be more difficult to achieve. If a lady has a BMI of >40 at the booking appointment then they should see an obstetric anaesthetist to create a plan for labour.
Pregnant women who are obese are at increased risk of postpartum haemorrhage. It is also more difficult to control PPH in pregnant women as compression of the uterus may be difficult to achieve.
Postpartum complications
- Hypertension
- Venous thromboembolism
If pregnancy induced hypertension or pre-eclampsia developed then this increases the risk of hypertension after labour. For this reason women need to be assessed a few weeks after delivery for monitoring.
Women should be advised to stay active.
Compression stockings may be prescribed and enoxaparin is recommended for 10 days after birth but may be needed for up to 6 weeks.