Physical Activity During Pregnancy

The benefits of staying active, for you and your baby

It wasn't that long ago that pregnant women were discouraged from exercising. But now we know that staying fit during pregnancy has many benefits – for both mums and their babies. So grab those walking shoes and get moving!

Engaging in regular physical activity has amazing benefits – at all stages of life. It maintains and improves your heart and lung fitness, muscle and bone strength, agility and flexibility, reduces the risk of obesity and diabetes, and increases your longevity. During pregnancy, it's beneficial for you and your baby, and in most cases poses no risk.

Is it safe to exercise during pregnancy?

Absolutley – for the majority of women experiencing a normal pregnancy without complications. However, you should always consult with your Lead Maternity Carer (LMC) – a midwife, obstetrician, or other health professional responsible for all antenatal care – for guidance around what forms of exercise are safe for you. In their Physical Activity Guidelines for Americans the US Department of Health and Human Services (2008) recommend that,

"Healthy women who are not already highly active or doing vigorous-intensity activity should get at least 150 minutes of moderate-intensity aerobic activity a week during pregnancy and the postpartum period. Preferably, this activity should be spread throughout the week [e.g.30-mins/day 5-days/week]. Pregnant women who habitually engage in vigorous-intensity aerobic activity or who are highly active can continue physical activity during pregnancy and the postpartum period, provided that they remain healthy and discuss with their health-care provider how and when activity should be adjusted over time."

Even though many physical activities are safe to do during pregnancy, there are some that should be avoided – mainly due to an increased risk of miscarriage, harm to the baby or mother, and/or premature birth. (See Table 1).

Table 1. Safe and unsafe physical activities during pregnancy (adapted from Comm Obstet Practice, 2015; US Department of Health and Human Services, 2008; and pregnancy-and-activity.pdf).

Safe activities (following consultation with LMC and exercise instructor)	Unsafe activities
Walking; Swimming; Stationary cycling.	Contact or collision sports – soccer, netball, rugby, hockey, basketball, etc.
Low-impact aerobics – after the first trimester of pregnancy, positions that result in decreased venous return and hypotension (low blood pressure) (e.g. lying on your back) should be avoided – always tell your instructor that you are pregnant	Activities with a high risk of falling – downhill skiing, surfing, ice skating, water skiing, off-road cycling, gymnastics, horseback riding, etc.
Yoga – after the first trimester of pregnancy, positions that result in decreased venous return and hypotension (low blood pressure) (e.g. lying on your back) should be avoided – always tell your instructor that you are pregnant	'Adventure' sports – scuba diving, bungy jumping, sky diving, etc.
Pilates – after the first trimester of pregnancy, positions that result in decreased venous return and hypotension (low blood pressure) (e.g. lying on your back) should be avoided – always tell your instructor that you are pregnant	'Hot yoga' or 'hot Pilates'
Racquet sports (tennis, squash, badminton, table tennis, etc.) – may be safe for women who played these sports regularly prior to pregnancy (consult with LMC before undertaking during pregnancy).	Racquet sports (tennis, squash, badminton, table tennis, etc.) – once the balance changes associated with pregnancy affect rapid movements and increase the risk of falling, a pregnant woman should avoid racquet sports as much as possible.
Running or jogging – may be safe for women who ran or jogged regularly prior to pregnancy (consult with LMC before undertaking during pregnancy)
Strength training – may be safe in women who regularly did strength training prior to pregnancy. However, heaving liftting should be avoided (consult with both your LMC and an exercise professional knowledgeable in pregnancy before undertaking strength training during pregnancy)

When shouldn't I exercise?

In a healthy, low-risk pregnancy, moderate aerobic exercise poses no risk to mother or baby. However, there are some instances where exercise can, and should be avoided.

If you have any of the following pregnancy complications or health conditions, you should avoid physical activity (it is essential you consult your LMC to see what's best for you, and get the right advice):

Hemodynamically significant heart disease (i.e. when blood circulation is compromised);
Restrictive lung disease;
Incompetent cervix or cervical cerclage (i.e. a stitch in the cervix);
Expecting twins, triplets, etc., and at risk of premature labour;
Persistent second or third trimester bleeding;
Placenta praevia after 26-weeks gestation;
Premature labour during current pregnancy;
Ruptured membranes;
Preeclampsia or pregnancy-induced hypertension (i.e. high blood pressure);
Severe anaemia (i.e. very low iron).

If you have any of the following pregnancy complications or health conditions, you may need to avoid physical activity (it's important to always seek professional advice first):

Anaemia (low iron);
Unevaluated maternal cardiac arrhythmia;
Chronic bronchitis;
Poorly controlled type 1 diabetes, hypertension (i.e. high blood pressure), seizure disorder (e.g. epilepsy), or hyperthyroidism;
Extreme morbid obesity;
Extremely underweight (BMI <12);
History of extremely sedentary lifestyle;
Intrauterine growth restriction in current pregnancy (i.e. that baby not growing as expected);
Orthopaedic limitations;
Heavy smoker.

If you're pregnant, and experiencing any of the following symptoms, you should stop your exercise and consult your LMC right away:

Vaginal bleeding;

Regular painful contractions;

Amniotic fluid leakage;

Difficult or laboured breathing before exertion;

Dizziness;

Headache;

Chest pain;

Muscle weakness affecting balance;

or calf pain/swelling.

Note: All pregnant women should consult their LMC throughout their pregnancy regarding any physical activity. This is because activities deemed safe in early pregnancy might not be safe later in pregnancy as physical changes occur.

What are the benefits of physical activity?

For pregnant mums

There's a lot of research out there that shows engaging in regular physical activity during pregnancy has a range of health benefits for expectant mums. These include:

Improved cardiovascular health;
Improved sense of well-being;
Better sleep;
Less pregnancy-related physical discomfort and back or pelvic pain;
Improved muscle strength and lean muscle mass;
Decreased bone density loss;
A decreased risk of hypertensive (i.e. high blood pressure) disorders, such as preeclampsia;
A healthy weight gain and reduced risk of obesity;
Increased likelihood of a normal delivery

Plus, exercise during pregnancy may be useful in preventing and treating antenatal depression (see Understanding antenatal depression; Taking care of yourself). Research also supports that strength training can reduce the requirement for insulin in women with gestational diabetes mellitus, and that physical activity before and during pregnancy may reduce the risk of developing gestational diabetes.

For your baby

You baby will also benefit if you exercise during pregnancy. They'll get all the cardiovascular fitness benefits you get – even after birth. Rest assured, exercising during pregnancy definitely won't deprive your baby of nutrients or oxygen, or affect their growth. In fact, moderate exercise in early pregnancy may actually reduce the likelihood of miscarriage.

However, keep in mind that frequent or high-intensity exercise during the second and third trimesters can significantly reduce birthweight and change your baby's body composition (i.e. less fat and more lean muscle). Why does this matter? If your baby doesn't have enough fat at birth, they can have difficulties with temperature regulation and maintaining blood glucose, which is important for brain function. Babies typically lose weight in the first few days after birth, and if they don't have enough fat, their muscle will be broken down, changing their blood chemistry, metabolism and increasing the risk of complications. Rule of thumb? If you're exercising a lot, simply dial down the intensity and frequency of your exercise after the first trimester.

Just as we don't want our babies to be born too small, we don't want them to be born too big either. Being large-for-gestational age (LGA) brings an increased risk of delivery complications and hypoglycaemia (low blood sugar) after birth. Regular physical activity during pregnancy reduces the risk that babies will be too big, and is particularly important for diabetic mothers, who tend to have larger babies due to excess glucose in their blood.

Summing it up

Physical activity is an essential part of a healthy lifestyle – before, during and after pregnancy.
For most expectant mums experiencing a normal pregnancy without complications, it's safe and beneficial (for mum and baby) to be moderately physically active – before, during and after pregnancy
During pregnancy, experts recommend that women engage in moderate physical activity 30 minutes per day, five days per week.
Physical activity isn't recommended for women with pregnancy complications or other health conditions. Always consult your Lead Maternity Carer for guidance around what's safe for you.
Most physical activities and non-contact sports are safe to continue during pregnancy. However, you should avoid contact, collision, or adventure sports, activities with a high risk of falling, and those that increase core body temperature.
Don't exercise and talk to your Lead Maternity Carer right away if you're experiencing: vaginal bleeding; regular painful contractions; amniotic fluid leakage; difficult or laboured breathing before exertion; dizziness; headache; chest pain; muscle weakness affecting balance; or calf pain/swelling.

Tips on how to be physically active

Make a routine. It's important for yours and your baby's health that you're physically fit before, during and after pregnancy. Experts recommend that you exercise for 30 minutes per day, five days a week while you're pregnant. It doesn't have to be 30 minutes all at once, three 10-minute bursts of activity spread throughout the day is fine too.
Pick the right sports. Most moderate intensity exercise and non-contact sports are safe to continue during pregnancy – such as swimming, walking, and yoga. However, you should avoid contact/collision sports (e.g. netball, mountain biking, rugby), adventure sports (e.g. scuba diving, sky diving), activities with a high risk of falling (e.g. downhill skiing, surfing, water skiing), and those that increase your core body temperature (e.g. 'hot' yoga) during pregnancy. If you're in doubt, just seek out medical advice.
Keep people informed. You should always be talking to your LMC throughout your pregnancy regarding any physical activity (new or continued). Always tell your instructor (yoga, gym, pilates, or aerobics) that you're pregnant.
Avoid racquet sports. Sports like tennis or squash can mess with your sense of balance and increase your chances of falling.
Make it comfortable. Wear loose-fitting, comfortable clothing when exercising (layers are a good idea), including a good supportive bra and well-fitting shoes. Drink plenty of water before, during and after physical activity, and get up slowly and gradually after exercising on the floor (e.g. yoga) to prevent dizziness. Don't get too hot, if the weather is warm then try to exercise in the morning or evening, when it is cooler. And don't forget to warm up and warm down.
Keep it moderate. Listen to your body and avoid getting too hot or exhausted. A good rule of thumb is the 'walk and talk test.' When exercising you should be moderately short of breath but still able to speak.
Get started. If you didn't do any (or much) regular exercise before pregnancy, you and your baby will still reap the benefits of exercising if you start now. Walking is your best option. Aim for five 30 minute walks per week. However, make sure to consult your LMC before embarking on a new exercise regime.
Take a class. Ask around about antenatal exercise classes like pilates, aquarobics, gym, or yoga. As well as keeping you fit, these classes a great way to meet other expectant mums. Always let your instructor know that you are pregnant, they can give you alternate exercises to do if some are not safe for pregnancy.
Keep running. If you were a runner before getting pregnant, it's probably ok for you to continue running throughout pregnancy. Check with your LMC though, and be aware you may have to tone things down in the second and third trimesters. (There are some indications that frequent or high-intensity exercise during the second and third trimesters significantly reduces birthweight and changes a baby's body composition.)

Resources

Auckland District Health Board: http://nationalwomenshealth.adhb.govt.nz/services/maternity/pregnancy-advice/exercise

See http://www.diabetes.org.nz/about_diabetes/gestational_diabetes for information about the benefits of exercise in relation to gestational diabetes

Ministry of Health http://www.health.govt.nz/your-health/pregnancy-and-kids/pregnancy/helpful-advice-during-pregnancy/being-active-during-pregnancy

Sport NZ has a brochure on Pregnancy and Activity pregnancy-and-activity.pdf

Tapuaki – Pacific Pregnancy and Parenting Education http://www.tapuaki.org.nz/im-pregnant-now-what/exercising

The Royal College of Obstetricians and Gynaecologists 'Guidelines on Recreational Exercise in Pregnancy' http://www.obstetrics.co.nz/assets/exercise.pdf