Obesity in pregnancy

Question 1

Define overweight and obese.

Answer 1

overweight = BMI of 25–29.9 kg/m²

obese = BMI of _>_30 kg/m²

Question 2

How common is obesity in pregnancy?

Answer 2

1.3% of the antenatal population is obese

Fewer than half of pregnant women (47.3%) have a BMI within the normal range

Question 3

When are pregnant women weighed?

Answer 3

At booking visit

Third trimester (if obese) - allows for planning for equipment and personnel during labour and delivery

Question 4

Are weight-loss programmes recommended during pregnancy?

Answer 4

No - they may harm the health of the unborn child

Question 5

Is it true that during pregnancy you have to ‘eat for two’?

Answer 5

There is no need to ‘eat for two’ or to drink full-fat milk during pregnancy

Energy needs do not change in the first 6 months of pregnancy

Energy needs increase only slightly in the last 3 months (and then only by around 200 calories per day).

Question 6

In patients with BMI over 30 wishing to concieve, what advice should you give?

Answer 6

• Set a realistic goal of 5-10% weight loss
• Inform of significant health benefits
• Explain that weight loss could increase chances of becoming pregnant
• Offer support and motivation as this may be difficult

Inform that weight loss between pregnancies reduces risk of stillbirth, HTN complications and fetal macrosomia, and increases chances of VBAC.

Question 7

In patients with BMI over 30 who are pregnant, what adivce can be offered regarding weight?

Answer 7

• Dieting should not be done during pregnancy
• Encourage healthy diet and physical exercise (moderate intensity exercise will not harm her or the unborn child)
• Healthy Start vouchers can be offered to those <18yrs or receiving benefits to increase fruit and veg intake
• Advise there is no need to ‘eat for two’
• Weight at booking appointment and no need for further weight measurement in pregnancy after this.
• Explain that risks of obesity will be managed by health professionals during pregnancy
• If BMI >30 then offer a referral to dietitian for assessment and advice on healthy eating and how to be physically active
• Encourage weight loss after pregnancy

Question 8

What advice can be given to postnatal patients with BMI >30 regarding weight loss?

Answer 8

Normal advice on diet and exercise, taking into account any caring needs and health problems e.g. pelvic floor weakness or backache

Reassure that gradual weight loss will not affect ability to breastfeed or quantity or quality of breastmilk

RCOG advice on recreational exercise:

• Walking, pelvic floor exercises and stretching - for those that had uncompliicated pregnancy and delivery
• Consult health care professional before resuming pre-pregnancy levels of exercise if complicated delivery or lower segment C-section

Question 9

What are the complications of maternal BMI of <20?

Answer 9

Higher risk of FGR and perinatal mortality

Question 10

What are the complications of BMI >30 in pregnancy?

Answer 10

• Gestational diabetes - test in all women BMI >30
• HTN and pre-eclampsia
• VTE
• Macrosomia
• Caesarean birth
• Mental health problems
• Small increased risk of maternal mortality and morbidity
• Fetal structural anomalies (below)

Investigations:

• Fetal assessment by palpation and ultrasound is more difficult
• Screening for chromosomal abnormalities is less effective (TVUSS may be necessary)
• Less accurate SFH measurements

Question 11

How does obesity affect medication given throughout pregnancy?

Answer 11

Folic acid if BMI >30 is 5mg OD instead of 400mcg - taken from pre-conception to 12 weeks

Aspirin 150mg OD (low dose) if BMI >35 and another moderate risk factor for PET - other moderate risk factors include G0, age >40yr, FH of PET, multiple pregnancy - given from 12 weeks to delivery