New US guidelines recommend regular moderate exercise on most days for pregnant women. Unlike 20 years ago, experts now know that exercise benefits both mother and baby, even beyond pregnancy.
Twenty years ago, doctors would have told pregnant women to rest as much as possible, for fear of affecting fetal growth, triggering early contractions or causing miscarriage.
The American College of Obstetricians and Gynecologists (ACOG), however, now explicitly states that physical activity has "minimal risks" and benefits most women.
The ACOG's latest guidelines, from late 2015, which are seen as a benchmark worldwide, state that concerns about premature delivery, miscarriage or stunted fetal growth as a result of exercise have "not been substantiated."
In fact, according to the ACOG, women should be "encouraged to engage in aerobic and strength-conditioning exercises before, during and after pregnancy."
Twenty to 30 minutes of moderate intensity exercise are recommended on most days of the week for anyone with an uncomplicated pregnancy - including those who are overweight or not normally active. It also makes no difference how old you are.
"What's new in these US guidelines is that they explicitly recommend certain sports, such as swimming or walking, which are easy on the joints," Nina Ferrari, sports scientist at the Cologne Centre for Prevention in Childhood and Youth, told DW. She specializes in the effects of exercise during pregnancy.
"But if you were a runner before your pregnancy, you can keep it up," Ferrari said. "That's new. We didn't have that before."
Ferrari said the intensity at which you work out should allow you to hold a conversation - experts call it the talk test. So, for example, if you are not a runner, consider a brisk walk or a swim. You can also do light weightlifting in the gym if that's your thing - just don't stay glued to your sofa for 40 weeks.
Exercise can also help you stay healthy and avoid gestational diabetes, which can harm the fetus and requires a strict diet and in some cases insulin injections, even if you're not normally diabetic.
According to ACOG, exercise can also reduce the risk of pre-eclampsia, a potentially fatal complication often caused by high blood pressure, as well as caesarean deliveries.
"Your metabolism benefits from exercise," Ferrari said. "It reduces the risk of getting gestational diabetes, you're less likely to suffer from back pain, and it helps you manage your weight."
As researchers continue trying to find ways to combat obesity, especially in young children, the potential benefits of exercise during pregnancy have attracted attention, Ferrari said. While there is no evidence to suggest your offspring will be sporty if you pound the pavement during pregnancy, exercise can affect the fetus's metabolism and, thus, have positive effects in childhood and beyond.
"It's called perinatal programming," Ferrari said, adding that a link between exercise during pregnancy and childhood health benefits has been established. "So, the topic is of growing importance, as we want to achieve a positive effect for mother and child at an early stage."
If gentle exercise is more your cup of tea, modified yoga can help you stay supple and help with back pain - a common problem during pregnancy, as mothers tend to arch their backs from the increased weight.
"Yoga is, of course, great for that," Susann Klose-Lehmann, a yoga teacher, told DW. Yoga, she said, can also help with breathing and strengthening exercises, which can help during labor.
"We do a lot of stretching and also strengthen the area that's needed during labor, the thighs and our core," Klose-Lehmann said.
So, there is no excuse - but choose your type of exercise wisely. Contact sports such as football, hockey, rugby or handball are out. Also steer clear of scuba diving, hiking at above 2,000 meters (6,500 feet) and anything that bears a high risk of falling.
Pregnant women should also pay attention to contraindications and take a break when needed. "If you are bleeding, if you have early contractions, or if your cervix starts dilating early, then you really have to stop exercising and consult your doctor," Ferrari said.
Also, be careful when it's hot, and rest if you have a cold or headache or feel dizzy.
Once you've had your baby, exercise will likely be the last thing on your mind as you struggle with sleep deprivation and nightly feeds.
Your pelvic floor, however, will be stretched from the weight of the baby and needs to be whipped back into shape. It's completely normal to feel increased pressure on your bladder postpartum, even temporary incontinence is not unusual.
It's essential therefore to start with pelvic floor exercises before doing anything too strenuous. In some countries, you're told to wait at least six weeks with those, but the new US guidelines are less cautious. In fact, they state that rapid resumption of these activities has "no adverse effects" if you've had an uncomplicated vaginal delivery.
A midwife or doctor can tell you when it's safe to do targeted abdominal exercises. The muscles in the abdomen split during pregnancy and have to reconnect postpartum. Women who have had a C-section may have to wait slightly longer before resuming exercise.
Women who are keen to resume team sports or other high-impact exercise should "wait at least 12 weeks," Ferrari said. She recommends starting with gentle walking and building up to running pace before joining a proper training session.
Professional athletes such as the UK heptathlete Jessica Ennis-Hill, for example, have demonstrated what the postpartum female body is capable of. She was crowned world champion just a year after giving birth to her son.
Alysia Montano, a US middle-distance runner, even competed in the 800-meter race in the US Track and Field Championship in 2014 while eight months pregnant.
But these athletes get paid to be top performers. For most pregnant women, the general rule of thumb is: Listen to your body, stop or rest when you need to, but don't give up exercise completely.
Studies show that women exercise less after childbirth than before, often leading to obesity and other complications. Staying active during pregnancy can help women maintain a certain level of fitness, which also makes it easier to recover from labor and get back into shape postpartum.
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