Mothers should be aware of the potential risks that excess weight can have on their pregnancies, through complications which threaten their health and that of the foetus. This applies to women who were already overweight before they got pregnant, as well as to those who gain excessive weight during pregnancy. At the least, obese mothers increase the risk of getting stretch marks and encounter more stress and pain on the lower back and joints, said Dr Julinda Lee, obstetrician and gynaecologist at Pacific Healthcare Specialist Centre.
Worse, they are at higher risk of developing high blood pressure and gestational diabetes during pregnancy, said Dr Tan Eng Loy, associate consultant gynaecologist at the Singapore General Hospital. High blood pressure can harm the mother's kidneys and other organs, result in low birth weight and hasten delivery.
Dr Chee Jing Jye, medical director of The Obstetrics and Gynaecology Centre, said that in more serious cases, the mother develops pregnancy induced hypertension, also called toxemia or pre-eclampsia. If left untreated, it can lead to seizures (eclampsia), kidney and liver damage, and ultimately death. Aside from risks to the mother, obesity makes it hard to hear the foetus’ heartbeat and measure the size of the uterus to prepare for childbirth, said Dr Christopher Ng, obstetrician and gynaecologist at GynaeMD Women’s and Rejuvenation Clinic. During childbirth, there is a host of complications that threaten a smooth delivery. Dr Ng said that obese women are more likely to require a Caesarean section.
Dr Tan pointed out that epidural anaesthesia used to relieve pain in labour is harder to administer in obese mothers, as is anaesthesia during a Caesarean section because it is more difficult for the anaesthetist to determine the spot on the patient’s back accurately. If general anaesthesia is used instead, there are also difficulties placing the oxygenation tube into the obese patient’s throat, he added. Dr Tan said: “After she has delivered her baby, an obese mother is also at higher risk of developing blood clots in her legs. These clogs can potentially dislodge and travel to her lungs, which can be life-threatening.”
Dr Ng added: “For the foetus, there is an increased risk of birth trauma, intrauterine death, birth defects like cleft palate, intestinal tract abnormalities and heart defects.” If the mother does not lose the excess weight after the birth, she risks developing conditions like diabetes, high blood pressure and heart disease.
However, Dr Tan cautioned against trying to lose weight during pregnancy. An exception will be for those with a body mass index of 40 or greater, at which “a modest weight loss” during pregnancy may be recommended. Even so, it should not be drastic and should be individualised for each woman under the close supervision of a doctor, he added.
HOW MUCH IS TOO MUCH?
Appropriate weight gain by a pregnant mum depends on her body mass index prior to pregnancy, said new research by KKH and Duke-NUS Graduate Medical School released last month
During the first trimester, a pregnant woman should be putting on between 900g and 2kg. For the rest of the pregnancy, she should be putting on approximately 200 to 250g per week.
About a quarter of a mother's weight gain will eventually be the baby's birth weight. The mother’s weight gain usually corresponds with the baby’s unless there is a placenta problem such that nutrients cannot be transferred from the mother, via the placenta, to the foetus.
The foetus' growth increases significantly from the 20th week of pregnancy, growing at a rate of between 150 and 200g per week. Growth of a foetus before the 20th week is generally measured by its length.