Weight Gain in Pregnancy
What are the health consequences?
There are health issues and increased risk to both women who gain too much weight and those who don’t gain enough. Morning sickness can impact on the ability to put it on, particularly if it carries through beyond the first trimester. Please don’t be overly concerned if you don’t gain (or even lose) in your first trimester. However, links exist between inadequate weight gain, premature birth and low birthweight babies. Women who gain excessively have increased risk of gestational diabetes, pre-eclampsia, miscarriage, stillbirth, high blood pressure and blood clots (13).
Women gaining excess weight are more likely to have an induction of labour, prolonged labour, an instrumental delivery (forceps or vacuum), a caesarean section or post-partum haemorrhage (13). These women will also have a harder time achieving a healthy weight after their baby is born. Retaining this weight increases risk of health problems including cardiovascular disease and diabetes and carrying this weight through to a subsequent pregnancy compounds this risk.
How much weight should women gain?
The following guidelines apply to women with uncomplicated pregnancies with a single baby on board.
| PRE-PREGNANCY BMI | Total Recommended Weight Gain (Kg) | Weight Gain (Trimester 2 And 3 in Kg/Week) |
| Underweight (<18.5) | 12.5 – 18 | 0.51 (0.44-0.58) |
| Healthy weight (18.5-24.9) | 11.5 – 16 | 0.42 (0.35-0.50) |
| Overweight (25-29.9) | 7 – 11.5 | 0.28 (0.23-0.33) |
| Obese (≥30.0) | 5 – 9 | 0.22 (0.17-0.27) |
What the table means
We advise women in the underweight category to put on the most weight during pregnancy to ensure the proper nourishment of the baby. On the other hand, women who are overweight or obese need to gain a much smaller amount of weight.
This table also details out the approximate weekly weight gain for the second and third trimester. Women do not need to gain weight for the sake of the baby in the first trimester, nor does your baby need you to consume more kilojoules at this time.
What makes up the weight gain?
An average new baby weighs approximately 3,500 grams when it is born. There are a few other things that contribute to weight gain in pregnancy, though.
These include;
- placenta
- amniotic fluid (water around the baby)
- additional uterine tissue
- extra breast tissue
- fat stores
- an increased blood volume
To weigh or not to weigh?
Originally the practice of routinely weighing pregnant women at antenatal appointments began in 1941 amid concerns that wartime rationing might result in maternal malnutrition. In the 1970s concerns emerged around excess weight gain, including its potential as an indicator for pre-eclampsia.
In the early 1990s, routine weighing of women during pregnancy came under scrutiny, with some believing that the process caused pregnant women anxiety with little evidence of an improvement in outcomes. This belief resulted in an attitude and cultural change in antenatal care and a decline in this practice.
As the debate continues and practice evolves around available evidence, this may no longer be the case. Given the known association between excessive weight gain during pregnancy, birth outcomes and long-term maternal health, the tide may be turning yet again regarding weight monitoring in clinical practice (13).
What you can do
- You don’t need to eat for two when you are pregnant. In the second and third trimester, women of a healthy weight only need to eat an additional 1,400 kilojoules (kJ)/ day and 1,900 kJ/day respectively. This amount is more for women with low BMI and less for women who are overweight or obese.
- Aim to eat nutritious food. This recommendation means more whole grains, lean meats, fish, eggs, legumes, low-fat dairy (cheese, yoghurt, milk), fresh fruit and vegetables and good fats (those found in nuts, seeds and avocado).
- Avoid takeaway, junk and convenience foods, e.g. biscuits, cakes, pastries, chips, chocolate, desserts and most takeaways.
- Soft drinks, fruit juices, cordials, and flavoured milk contain lots of kilojoules and little nutrition. Stick to water and low-fat plain milk.
- Choose healthy snacks such as fruit, vegetables, wholegrain crackers and low-fat cheese, low-fat yoghurt, nuts and seeds.
- Watch your serving sizes. A portion of lean meat, for example, is the size of your palm and a serve of pasta is half a cup (cooked).
- Participate in regular exercise. Half an hour of moderate activity on most, if not all days, is enough to make a difference. Pregnant women who have not participated in regular exercise previously should consult with their health care provider before starting.
To read more about healthy weight gain during pregnancy, please click here.
Dr Janelle McAlpine (PhD), Clinical Midwife
Photo by Ilya Andriyanov used under license from Shutterstock.com