Overweight and obesity, in particular, significantly increase risks to the pregnant woman, the fetus and the baby (e.g. fetal malformation, asphyxia, preterm delivery, post-term pregnancy, maternal gestational diabetes, pre-eclampsia, thromboembolic complications).
Treatment and support aimed at weight reduction should begin as early as possible, even before pregnancy. Lifestyle guidance should be started no later than early pregnancy.
If the body mass index (BMI) before pregnancy or in early pregnancy is ≥ 40 kg/m2 , the woman can visit the maternity hospital around week 37 of pregnancy to plan the delivery, as considered necessary. Consulting an anaesthesiologist can also be considered.
Prevalence of overweight and related pregnancy risks
Maternal obesity (BMI ≥ 30 kg/m2 ) has become more common.
Complications threatening the mother's life, need for intensive care and maternal mortality
Treatment and follow-up before pregnancy
Favourable effects of weight loss on fertility Fertility Counselling and on reducing pregnancy and delivery complications should be discussed with overweight or obese women of fertile age (at visits related to weight management, family planning, childlessness or gynaecology, for instance).
Before stopping contraception, any medication that is forbidden during pregnancy (such as GLP-1 analogues used for weight reduction) should be withdrawn.
Folic acid supplementation (at least 400 µg/day) should be started as early as possible when planning pregnancy (no later than 2 months before stopping contraception).
For women who have undergone bariatric surgery, pregnancy is recommended only 1-2 years after surgery.
Before surgery, a discussion should be had with patients of fertile age to ensure that they are using reliable contraception (such as a hormonal IUD).
The aim should be to stabilize weight and to use appropriate dietary supplements regularly before stopping contraception.
The significance of a healthy diet, physical activity and weight management for the health of the mother herself, the baby and the family should be discussed at the maternal health centre, with practical support provided.
If folic acid supplementation (minimum 400 µg/day) was not started when planning pregnancy, it should be started as soon as pregnancy is confirmed and continued until week 12 of pregnancy.
If BMI is ≥ 30 kg/m2 , higher doses of folic acid (1-4 mg) can be used based on medical consideration if, for example, the woman has diabetes or an intestinal disease or is on medication increasing the need for folic acid.
See also local recommendations concerning weight loss, weight management, physical activity and nutrition during pregnancy.
Recommended weight gain during pregnancy:
For overweight women (BMI 25-29.9 kg/m2 ) 7-11 kg
For obese women (BMI ≥ 30 kg/m2 ) 5-9 kg.
Higher than recommended weight gain is associated with increased risk of fetal macrosomia, caesarean section, and complications associated with blood pressure, as well as of overweight after pregnancy.
Lower than recommended weight gain may predispose to low fetal weight and premature delivery but evidence for this is partly contradictory. In obese women (BMI ≥ 30 kg/m2 ), lower than recommended weight gain does not necessarily involve such risks and, indeed, lower weight gain may reduce the risk of fetal macrosomia, caesarean section, pre-eclampsia and overweight after pregnancy Gestational Weight Gain below Instead of Within the Guidelines Per Class of Maternal Obesity: Obstetrical and Neonatal Outcomes.
Prophylactic aspirin to prevent pre-eclampsia should be started if other risk factors for pre-eclampsia are detected in addition to obesity (BMI ≥ 30 kg/m2 ); see Antenatal Clinics: Care and Examinations.
A glucose tolerance test should be done in all pregnant women in week 24-28 of pregnancy.
For women with BMI ≥ 30 kg/m2 or other risk factors Antenatal Clinics: Care and Examinations, a glucose tolerance test should be done as early as week 12-16 of pregnancy and repeated in week 24-28 if the first test was normal.
Pregnant women who have undergone bariatric surgery should be referred as early as early pregnancy for follow-up at the maternity hospital outpatient clinic.
Delivery planning
If the body mass index (BMI) before pregnancy or in early pregnancy is ≥ 40 kg/m2 , the woman can visit the maternity hospital around week 37 of pregnancy to plan the delivery, as considered necessary. Consulting an anaesthesiologist can also be considered.
When admitted for delivery, the mother should be assessed by an anaesthesiologist to establish sufficient i.v. access and to plan suitable analgesia, for example.
The need for prevention of venous thromboembolism should be considered at the hospital, taking into account any additional risks related to the course of the delivery (such as caesarean section).
In obese women, lactogenesis may be slower for hormonal reasons and breast-feeding may be more challenging for mechanical reasons (e.g. large breasts).
Breast-feeding facilitates weight management and reduces the child's risk of subsequent obesity.
At visits to maternal and child health centres and other primary health care, individual transitioning to the healthiest possible diet should be discussed and supported, and the significance and possibilities of physical exercise and weight management should be discussed. The post-delivery check-up is important in this respect.
Mobile or internet-based or other home weight loss and weight management methods may be suitable in the situation in life after delivery.
Cantor AG, Jungbauer RM, McDonagh M, et al. Counseling and Behavioral Interventions for Healthy Weight and Weight Gain in Pregnancy: Evidence Report and Systematic Review for the US Preventive Services Task Force. JAMA 2021;325(20):2094-2109 [PubMed]
National Institute for Health and Welfare in Finland and Finnish National Nutrition Council. Eating together - food recommendations for families with children. 2nd updated edition, 2019 http://urn.fi/URN:ISBN:978-952-343-264-2.
Creanga AA, Catalano PM, Bateman BT. Obesity in Pregnancy. N Engl J Med 2022;387(3):248-259 [PubMed]