Weight gain in pregnancy: What happens if you put on too much or too little, and what to do to keep healthy
Is it true that pregnant mums are “eating for two” and it’s okay to pile on the kilos? A gynaecologist, dietitian and physiotherapist share advice about healthy weight gain during pregnancy and how mums can ensure they and their babies grow well together.

What’s too much when it comes to weight gain during pregnancy? CNA Women finds out. (Photo: iStock/PeopleImages)
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When you’re growing a baby in your body, it’s no secret or surprise that a part of your pregnancy journey will include putting on weight. But just how much weight gain during pregnancy is too much – and can it ever be too little?
You may be aware of HealthHub SG’s recommendation for weight gain during pregnancy: 5kg to 18.1kg for a single non-complicated birth, depending on your body mass index (BMI).
For instance, if your BMI falls within the healthy range of 18.5 to 24.9, the recommended weight gain during pregnancy is between 11.3kg and 15.9kg. If your BMI exceeds 30, the recommended weight gain is between 5kg and 9.1kg.
However, is BMI the only factor to consider? And what does it mean for pregnant women who gain weight outside of the recommended range?
CNA Women asked a gynaecologist, nutritionist and physiotherapist these questions to learn about the weight-related scenarios different women might experience when expecting and how they can stay healthy while pregnant.
WHERE DOES THE WEIGHT GAIN COME FROM?

Dr Sarah Li, a consultant from the National University Hospital (NUH) department of obstetrics and gynaecology, said that for most women with an uncomplicated pregnancy, the weight gain is due to the body supporting the developing baby.
Weight gain can vary with each trimester. In the first trimester, many women gain little weight. “Some may even lose weight due to loss of appetite and morning sickness, which can last all day and lead to nausea and vomiting, making it hard for expectant mothers to eat,” the obstetrician and gynaecologist said.
However, some women may gain a considerable amount of weight, such as 5kg, in the first three months of pregnancy.
“This could be due to other factors besides food intake, such as the increase of hormones that can lead to bloatedness and water retention,” Dr Li explained. “Sometimes, it’s also due to growing breasts for milk production.”
In the second and third trimesters, when morning sickness has eased, women typically gain 2-3kg a month.
By your due date, a rough estimate of the weight breakdown could look like this: Around 3.5kg for the baby’s weight; another 4-7kg for your growing womb, placenta, amniotic fluid and breast tissue; 2.5-4kg in fat stores and 2kg in increased blood volume.
Being more sedentary due to pregnancy tiredness and fatigue can also contribute to weight gain during any of the trimesters, Dr Li added.

When you gain too much – or too little – weight outside of the recommended range of five to 18kg, however, there are multiple causes for concern, Dr Li said.
Too much weight gain may lead to an increased risk of gestational diabetes and high blood pressure during pregnancy. It’s also associated with delivering a large baby, which can result in birth complications like severe tears or postpartum haemorrhage (excessive bleeding after birth).
Dr Li added that putting on too much weight can also increase the mum’s risk of postpartum weight retention and obesity, potentially leading to cardiovascular diseases.
Conversely, gaining less than the recommended amount of weight in pregnancy is associated with delivering a baby that is too small, Dr Li said.
Such babies may have difficulty starting breastfeeding, may be at increased risk for illnesses, and may experience developmental delays which can lead to missing important growth milestones for the child’s age.
EATING WELL FOR PHYSICAL AND MENTAL HEALTH

When it comes to keeping well throughout pregnancy, Dr Li noted that diet and exercise are key.
“It is a myth that pregnant women need to ‘eat for two’ during pregnancy,” Anthea Zee, a dietitian at the nutrition and dietetics department at KK Women’s and Children’s Hospital (KKH), said.
She highlighted that a gradual increase in calories is sufficient for pregnant women and their babies.
Zee added that during the first trimester, no additional calories are necessary in the diet. However, in the second trimester, it’s recommended that you consume an extra 300 calories per day, and in the third trimester, an extra 450 calories daily is sufficient.
It is a myth that pregnant women need to ‘eat for two’ during pregnancy.
Some examples of wholesome foods that provide around 150 calories would be:
- One slice of wholemeal bread with a slice of cheese
- One palm-sized portion of meat or fish or 300g of tofu
- A cup of low-fat milk
- A small tub of low-fat yoghurt and one egg
Aside from how much, what’s important to consider is the quality of the food. In particular, foods rich in calcium, iron, vitamin C and vitamin D are essential, said Dr Li.
These nutrients help the development of bones, gums and teeth for both mum and baby. They also aid in red blood cell production and oxygen delivery to the foetus and promote the baby’s healthy eyesight and skin.
All this is well and good for pregnant mums who don’t mind keeping track of their calories and who tend to eat healthily anyway. It, however, becomes more challenging when you have food cravings – from durian to mee siam – during your pregnancy.
“Sugar cravings happen and you should not be expected to completely avoid sugar unless you have gestational diabetes,” Zee said.
If you struggle to manage your cravings, Zee has these tips:
- Get adequate sleep as research has shown that sleep deprivation can result in cravings for unhealthy foods
- Drink plenty of water (at least eight to 10 cups daily – if you’re dehydrated, you may feel fatigued and have more food cravings
- It’s alright to indulge in your food cravings once in a while to prevent feeling deprived
- Have regular and well-balanced meals to prevent sudden feelings of hunger
- Have healthier alternatives to satisfy your sugar cravings, including fruit-based ice-cream (frozen fruits blended with milk or yoghurt), yoghurt topped with granola or fresh fruit, and dates with nut butter.
- Consider alternatives for savoury treats such as grilled seaweed, homemade lightly salted popcorn, rice crackers and baked nuts
- Constitute non-alcoholic beers as an alternative to reduce your intake of alcohol while still being able to enjoy the taste and experience of beer
“Indulging in an occasional sweet treat shouldn’t negatively impact your pregnancy,” Dr Li said. Moderation is key and something delicious will also help with your mental well-being, which is also important for you and the growth of your baby.
EATING AND EXERCISE GO HAND-IN-HAND

For women who struggle to curb their diet and manage their food cravings, there’s exercise. Dr Li recommends it even if the woman has never worked out before pregnancy.
“Not only does exercise help manage healthy weight gain, it also improves cardio-respiratory fitness, and the mental well-being of the mum,” said Jenna Kee, senior physiotherapist of KKH’s physiotherapy department.
Kee advised healthy women with uncomplicated pregnancies to aim for a minimum of 150 minutes of moderate-intensity physical activity a week. This can be achieved through 20- to 30-minute sessions, at least three days a week, and should include both aerobic and resistance-training activities.
“There are many types of aerobic physical activities that pregnant women can safely engage in,” Kee said. These activities vary depending on the individual’s fitness level and include brisk walking, light jogging, swimming, stationary cycling and modified yoga or pilates.
Resistance training can also help with building strength and preparing the body for the physical demands of labour, Kee added. Examples include exercises using weights and resistance bands or bodyweight exercises such as squats, lunges and push-ups. She also emphasised the importance of warm-ups and cool-downs before and after the exercise to minimise injury.
“Mums-to-be should know that exercise doesn’t have to be strenuous or stressful,” Dr Li said. “As long as your body is consistently moving and active, you can better manage your weight gain and keep both your body and baby well.”
Platforms like HealthHub SG and HealthXchange Singapore offer resources from certified experts that women can refer to, including step-by-step guides on prenatal yoga, daily deep breathing and simple stretching exercises.
WEIGHT GAIN IS ONE PART OF THE JOURNEY

What’s most important to know, Dr Li said, is that weight gain will look and feel different for every woman.
“If you gained more than the recommended amount despite doing exercise and following the dietary advice, don’t feel bad about yourself,” Dr Li said. “You just grew an entire human in your body for around nine months – this inevitably comes with bodily changes.
“As you go on your parenting journey, there will be opportunities for you to be healthier as long as you continue healthy habits to keep your body well.
“What’s essential is cultivating healthy lifelong habits to sustain a strong body and a healthy mind to go through the lifelong journey of parenthood and motherhood – which may be physically and mentally draining but extremely fulfilling.”
CNA Women is a section on CNA Lifestyle that seeks to inform, empower and inspire the modern woman. If you have women-related news, issues and ideas to share with us, email CNAWomen [at] mediacorp.com.sg.