Exercise during pregnancy: danger signs

Exercise during pregnancy has many benefits. It keeps your muscles strong and flexible, relaxes you, soothes some of pregnancy's physical discomforts and makes it easier for you to get back into shape after your baby's birth.

Now that you're pregnant, though, you'll have to be easier on yourself. Your entire body has changed. Your centre of gravity has shifted, you're carrying more weight, and you tire more quickly.

That's why you must listen closely to your body (Artal and O'Toole 2003). It will let you know when you're working too hard. As a rule of thumb, try not to get so breathless that you can't keep a conversation going while you're exercising. We list the warning signs that may tell when you you're overdoing it.

When should I call my midwife or doctor?

If you have any of the symptoms listed below either during or after exercise, call your midwife or doctor.

Dizziness
You'll need to have your health checked if you feel dizzy over a long period, rather than for a few moments. If you have headaches or heart flutters (palpitations) at the same time as feeling dizzy, it may be sign that you haven't got enough iron in your blood (anaemia).

Heart palpitations
If you feel strange, fluttery sensations in your chest, you may be exercising too hard. Slow down gradually and stop. Let your doctor or midwife know about this.

Leaking from your vagina
If your vagina is leaking fluid, your waters may have broken. Some of the amniotic fluid that surrounds your baby in your uterus (womb) may be escaping. It's easy to confuse this with leaking small amounts of urine (stress incontinence) while you're exercising, but see your doctor or midwife to check which it is. You can do pelvic floor exercises to help prevent urine leaks.

Nausea or vomiting
If you feel sick while exercising, or even vomit, it means that you're overdoing things. It could also mean that your blood sugar levels are low, or that you have low blood pressure.

Sudden change in body temperature
If your hands turn clammy or you get hot or cold flushes, your body is telling you that it's having a hard time regulating its internal thermometer. This may be harmful to your baby (Berk 2004, Clapp 2002, Lynch et al 2003, Soultanakis-Aligianni 2003). If you overheat, your baby will, too. Your body will try to cool itself by diverting some of the blood flowing to your uterus to your skin's surface instead.

Swelling
Your feet and hands may puff up a little after exercise, but if it's worse than normal, see your doctor. Swelling can be a sign of pre-eclampsia. This is a condition in which your blood pressure rises and your body hoards fluid. It restricts the blood supply to the placenta and, if it goes untreated, can be harmful to your unborn baby.

When should I seek urgent help?

The symptoms listed below are more serious. If you have any of them, and you can't get to see your doctor or midwife, don't wait around. Call your hospital's maternity unit, or go straight to your nearest hospital emergency department.

Calf pain
If you have a sharp pain, swelling or redness in your calf, it may be a sign that a blood clot has lodged in a deep vein in your leg. It's important to have it checked as soon as possible.

Blurred vision
If your eyesight gets blurry in the middle of exercising, you may be dehydrated. Not having enough fluid in your body can make your blood pressure drop and your heart work extra hard (Flanagan et al 2007). If this happens, it may mean that not enough blood gets to your baby's vital organs. Blurred vision can also sometimes be a sign of pre-eclampsia.

Fainting
Whether you're in the middle of a pregnancy exercise class or not, fainting may mean you have a problem and it needs to be checked. It could mean something as simple as dehydration, low blood sugar or low blood pressure. But you may not be getting enough oxygen to your brain, which means your baby isn't getting enough either.

Sharp pains in your belly
Your ligaments may just be stretching, but you could also be having contractions. If the pains continue, you may need your midwife to check you with a monitor to find out whether or not you're in labour.

Vaginal bleeding
Some women do have light spotting throughout their pregnancy, but actual bleeding is more worrying. You'll need to get urgent help if this happens, because early in your pregnancy, it could be a warning sign of miscarriage. In the second and third trimesters, bleeding could be a sign of:

• labour that starts before 37 weeks, or premature labour
• a low-lying placenta, or placenta praevia
• the placenta coming away from the uterus (womb) wall, or placental abruption

Your baby's movements slow down or stop
If you notice that your baby isn't moving, or isn't moving as much as he usually does, let your doctor or midwife know as soon as possible. Remember that it's normal for your baby to appear a little quieter when you're exercising, but his movements should return to normal afterwards (Artal and O'Toole 2003, Davies et al 2003).

Check out our slideshow of the best pregnancy exercises.