For most dads, feeling their baby kicking for the first time is a major milestone. It may be a few months yet before they can start roughhousing with the kid, but feeling a baby move in the womb is a first encounter of sorts — an emotional experience for all parents-to-be who are eager to meet their child. From growing bones to tiny hiccups, there are scientific reasons why babies move, kick, and flutter in utero. Parents curious about baby kicking need look no further. Researchers reveal why babies kick, when they start kicking, and what it means — and also offer up some tips on how to instigate more baby kicking in the womb. Bring it on, kid.
The Meaning of Baby Kicking
Babies don’t just move because it’s cramped in there — every sharp kick helps shape your baby’s growing bones. A recent study in the Journal of the Royal Society Interface found that the force of fetal kicks markedly increases between 20 and 30 weeks gestation, and then declines by 35 weeks. This suggests that a baby’s kicks are the most vigorous during those middle stages of fetal development, just when bones and joints are beginning to take shape. It makes sense. Animal studies have shown that stationary fetuses emerge with bone and joint problems; conversely, weight-bearing exercises like brisk walking have been shown to strengthen bones.
Fetal movement may also be linked to long-term behavior. One fascinating but less authoritative study found that “fetal motor activity appears to predict temperament attributes related to regulatory behaviors in early childhood.” So it’s possible that kicking also has something to do with neurological development (although causation is entirely unclear, and it’s also possible that babies with poor neurological development move less in utero).
Regardless, these studies broadly suggest that when your baby’s kicking, it’s probably not just a friendly salutation from the inside — it’s an important part of fetal development. So moms who get kicked a little too hard can rest assured that it’s a productive part of the process.
When Can You Feel a Baby Kick?
Babies start moving at 12 weeks, but mom is unlikely to feel anything besides “flutters” until 16 to 20 weeks. That’s when you’ll feel your first kick. Baby kicks should strengthen, with a complement of twitches (those are baby hiccups!), through the third trimester, slowing down slightly around week 36 when the womb becomes too crowded for vigorous thrashing. Babies are most active in the morning and in the evening, and their movements are easiest to detect when the mother is sitting or lying down.
Starting at the beginning of the third trimester, physicians generally recommend that parents begin monitoring fetal movements. If at any point a mother suspects the baby is moving less than usual (even after 36 weeks), she should call her doctor immediately. Babies don’t move all the time but, as a rule of thumb, shoot for 10 movements per hour in the third trimester. And keep a careful eye on whatever is normal for your baby. If a child is always bouncing against mom’s belly in the morning, even one morning without fetal movement is cause for concern.
How to Make More Baby Kicking Happen
There are a handful of age-old tricks that ultrasound techs use to get sleepy babies moving in utero. Drinking juice or another sugary beverage is a time-honored way to give your kid a minor sugar rush and, similarly, raising your adrenaline by watching a scary movie can put your fetus on high-alert. In the third trimester, when the baby’s eyes and ears are more or less done developing, shining a light on mom’s belly or playing music may help your baby perk up and kick.
One recent study found that babies move when their mothers are lying on their sides, and freeze up when mom lies on her back. The reason is slightly horrifying — mothers decrease their fetuses’ oxygen supply when they lie on their backs in late pregnancy, so their babies stop moving to conserve oxygen. Regardless, the joy (not to mention reassurance) of regular baby kicks is just one more reason for pregnant women to sleep on their sides.