Your weight, of course, increases in pregnancy, but only a small amount of this weight gain is fat. Unless you are very underweight or overweight, doctors are not too concerned about weight gain in pregnancy. This is because the growth of the baby is not dependent on your
weight gain, but rather upon the efficiency of transfer of vital nutrients across the placenta. However, on average, women gain around 12 kg (26 lb) during pregnancy. Some women gain less and some more, depending on several factors, including how heavy you are to start with and how big your baby is.
Of the 12 kg (26 lb) weight gain in an ‘average’ pregnancy, most of this is made up by the womb, baby, placenta and amniotic fluid, which by full term weighs almost 6 kg (13 lb) in total. Extra fat and the increased weight of your breasts account for 3.9 kg (8 lb 7 oz) of the weight gain, while the rest is made up of an increase in the volume of your blood and by retained fluid.
These estimates vary enormously from woman to woman and the figures given below are simply an illustration of how the weight gain is made up. Remember that the fat that you gain in pregnancy is there for a reason. Your body is deliberately storing fat on your hips, your back and your breasts to prepare you for breastfeeding. Milk is rich in fats, which are needed by the growing baby. Not surprisingly, women who breastfeed lose weight faster after pregnancy than those who do not.
Exercise during pregnancy
Just as with diet, exercise is critical to good health. Both combine to influence our weight. Food is our fuel. If we don’t burn it off with exercise, we store it as fat. To maintain a steady body weight, food supply should be balanced with energy expenditure.
Exercise is good
Pre-pregnancy most women know that exercise is good for their health. Many women are concerned, however, that they may have to stop exercising in pregnancy as this might threaten the pregnancy. In general, this is not true and exercise is encouraged during pregnancy.
There is extensive research to show that, in most cases, exercise is safe for both mother and baby. Doctors therefore recommend initiating or continuing exercise in pregnancy because of the health benefits. Indeed, athletes who continue training in pregnancy actually have an improved performance after the pregnancy as the pregnancy-induced changes in the cardiovascular system enhance the effect of training. Not only does regular exercise make you feel better and fitter, it also helps prepare you physically for labour and delivery.
Walking, cycling, swimming and stretching are all good forms of exercise in pregnancy. However, you should avoid activities that are likely to lead to any falls or impacts on your abdomen, such as contact sports like kick boxing. In later pregnancy, activities where balance is important, such as horse riding or down-hill skiing, can be hazardous due to the change in your centre of gravity.
• Swimming is a particularly good form of exercise when you are pregnant. This is because the water supports your body and you can exercise your arms, legs and back and also improve cardiovascular fitness without straining your body.
• Yoga is also a good form of exercise and an ideal preparation for labour because of the muscular stretching, control of breathing and posture, and emphasis on relaxation.
So for most women, the exercises they have been doing pre-pregnancy can be continued. For those who have not been taking regular exercise, it is worth thinking seriously about starting a routine during pregnancy.
The important thing about taking exercise is to do it regularly. Thirty minutes of moderate exercise three times a week or more makes a big difference to your fitness and your weight. You should also increase your exercise as you go about your daily activities. Walk wherever possible and take the stairs instead of the lift. Regular exercise is also good for reducing stress and makes you feel more energetic, as well as increasing your sense of wellbeing.
Beginning to take exercise
watch out!
• If you have any medical or obstetric problems, consult your doctor before starting any exercise programme.
• If you have any unusual symptoms when exercising, stop and obtain advice from your doctor.
• Stop exercising if you feel very short of breath, get chest pain, feel faint or dizzy, have a bad headache, or have any vaginal bleeding, or leg swelling, or abdominal pain and seek your doctor’s advice.
If you are not used to regular exercise, start gradually with a low-intensity, low-impact activity like swimming or walking. Begin with a good 15 minutes of aerobic exercise, like walking or swimming three times weekly, and build up to about 30 minutes three or four times a week, and then every day. A brisk 30 minutes of walking, ideally with part of it up hill, three times a week, leads to improvements in fitness within two weeks. This builds up your stamina, which is one of the major objectives of exercising in pregnancy.
Key points to remember when taking exercise are:
• aerobics (exercise that improve the fitness of your cardiovascular system) and strength-conditioning exercises are recommended for pregnancy health, aiming for a good level of fitness rather than peak competitive athletic performance
• appropriate levels of exercise are not linked to pregnancy complications and, in fact, might reduce the risk of certain complications
• after delivery, moderate exercise does not affect breastfeeding in any way.
Before you start each exercise session, it is worth spending four to five minutes on muscle warm-ups. A ‘cool down’ period of gradually declining exercise at the end of the session is also advisable. It is usually best to limit your activity to 15-minute periods with five minutes of rest in between.
Ideally you will have an individual fitness programme that takes into account your age, level of fitness and any other relevant factor, such as a pre-existing medical condition. The target heart rates for aerobic exercise in pregnancy are shown in the table above, but if you are not used to exercise, you should set a target about 60 per cent above your usual heart rate. So, if your usual rate is about 80, a suitable maximum would be about 125 beats per minute.
Exercise to avoid
You should avoid prolonged, high-intensity training and the general rule for exercise is to not overdo it when you are pregnant. If you are too breathless to hold a conversation when exercising, then you are probably doing too much.
• Check your heart rate and don’t exceed your target rate.
• Do not get overheated or dehydrated; in particular, do not exercise if you have a high temperature.
• Do not exercise for prolonged periods; do no more than 45 minutes at a time.
• Ensure that you always have a good fluid intake after vigorous exercise.
In terms of what exercises to do regularly, avoid sit-ups and straight leg raising while on your back. These can strain your abdominal muscles, which are already stretched by the growing pregnancy. The two large muscles that run longitudinally down the middle of your abdomen (known collectively as the rectus abdominus), normally separate in pregnancy to help accommodate the growing pregnancy. Exercises that stretch these muscles, such as sit-ups and straight leg raising, stresses them further, which slows down the speed at which they return to normal after