The amount of weight gain during pregnancy can affect the immediate and future health of a woman and her infant. Over the past decade, the demographics of the population of women who become pregnant has changed dramatically with more women being overweight or obese at conception.

The global prevalence of overweight and obesity in pregnancy is rising and this represents a significant challenge for the management of pregnancy and delivery. Labour complications arise more often when pregnancies are complicated by overweight and obesity.

There is an association between excessive weight gain during pregnancy and increased birth weight and weight maintenance after delivery, but also between insufficient weight gain and reduced birth weight.

Body Mass Index (BMI) ) is the most commonly used to assess body weight, which mainly reflects the way of nutrition. Based on your pre-pregnancy BMI, can be estimate how much weight women should gain during pregnancy.

BMI calculator

BMI is calculated as weight in kilograms divided by height in meters squared:

Here’s what it means:

• Under 18.5 = underweight
• Between 18.50 and 24.9 = normal weight
• Between 25 and 29.9 = overweight
• 30 and greater = obese (includes all classes).

Pregnancy weight gain

Many women feel that during pregnancy they can eat as much as they want due to the increased caloric needs of the fetus.

Weight Gain Recommendations For Women Pregnant With One Baby

Healthy weight gain during pregnancy is as follows:

• in women with normal BMI between 18.5 and 24.9, recommended pregnancy weight gain should be 25 to 35 lbs. (11 to 16 kg)
• in underweight women with BMI less than 18.5, recommended pregnancy weight gain should be 28 to 40 lbs. (13 to 18 kg)
• in overweight women with BMI between 25 and 29.9, recommended pregnancy weight gain should be 15 to 25 lbs (7 to 11 kg)
• in obese women with BMI 30 or more, recommended pregnancy weight gain should be 11 to 20 lbs. (5 to 9 kg)

Weight Gain Recommendations For twin pregancies

For twin pregnancies, the IOM recommends a pregnancy weight gain of

• 16.8–24.5 kg (37–54 lb) for women of normal weight,
• 14.1–22.7 kg (31–50 lb) for women overweight,
• 11.3–19.1 kg (25–42 lb) for obese women.

The IOM guidelines recognize that data are insufficient to determine how much weight women should gain in multiple pregnancies (triples and above).

The body weight of a pregnant woman should be under constant control of the attending gynecologist. Its increase of body mass should be strictly controlled and recorded in the patient’s pregnancy chart. Excessive fluctuations are not recommended. With a normal body mass before pregnancy, the optimal gain during pregnancy should be 10-14 kg. Then the newborn can reach the right birth weight of about 3.1-3.6 kg.

A woman’s total body weight at the end of pregnancy consists of:

• about 3.5 kg – baby’s weight
• about 1-1.5 kg – uterus
• about 1-2 kg – breasts
• about 1-1.5 kg – amniotic fluid
• about 0.5-1 kg – placenta
• about 1.5-2 kg – blood and additional fluids
• about 2-4 kg – additional adipose tissue that lines the abdominal cavity, protects the fetus and provides energy.

Too much weight gain during pregnancy:

• increases the risk of long-term obesity in both mother and child, thus exposing both of them to the risk of related diseases,
• contributes to back pain, leg swelling, varicose veins and hemorrhoids
• can cause pregnancy complications such as:
  • gestational diabetes,
  • hypertension,
  • neonatal macrosomia,
  • premature birth or the need to complete the pregnancy by caesarean section.

Too little weight gain during pregnancy:

• is associated with low birth weight infants, which increases perinatal mortality and morbidity,
• may cause developmental problems in childhood,
• is one of the risk factors for cardiovascular disease, diabetes and hypertension in later life.

Do not lose weight during pregnancy!!!

Agata Mroczek

References:

1. Berger DS, West EH. Nutrition during pregnancy. In: Landon MB, Galan HL, Jauniaux ERM, et al, eds. Gabbe’s Obstetrics: Normal and Problem Pregnancies. 8th ed. Philadelphia, PA: Elsevier; 2021:chap 6.
2. Bodnar LM, Himes KP. Maternal nutrition. In: Resnik R, Lockwood CJ, Moore TR, Greene MF, Copel JA, Silver RM, eds. Creasy and Resnik’s Maternal-Fetal Medicine: Principles and Practice. 8th ed. Philadelphia, PA: Elsevier; 2019:chap 12.
3. Langley-Evans SC, Pearce J, Ellis S. Overweight, obesity and excessive weight gain in pregnancy as risk factors for adverse pregnancy outcomes: A narrative review. J Hum Nutr Diet. 2022;35(2):250-264. doi:10.1111/jhn.12999
4. Rasmussen KM, Yaktine AL, Institute of Medicine (US) and National Research Council (US) Committee to Reexamine IOM Pregnancy Weight Guidelines, eds. Weight Gain During Pregnancy: Reexamining the Guidelines. Washington (DC): National Academies Press (US); 2009.