When does the fetus develop reflexes?

Dr. Michael Roizen, MD
Internal Medicine
A fetus develops plenty of reflexes, and all of these reflexes depend on the central nervous system. These are the main ones: 1. Movement:Fetuses develop the ability to flex and extend their limbs and suck their thumbs in utero, but these reflexes usually disappear by 8 months after birth, when gross motor skills start to take over. At this point, movements such as thumb sucking become more voluntary than reflexive. By the way, even moderate alcohol use during pregnancy seems to impair a child's sucking reflex at birth - a potential feeding problem. 2.Walking:Before babies learn to crawl, they'll pretend to walk. They practice that movement in utero and continue it for the first three months (the reflex has to be lost before they gain the ability to walk consciously). It's also called the stepping reflex - you see it in action when you a hold a baby upright by her waist and watch her flail her legs like she's trying to walk. 3.Moro reflex:You know the sensation where you feel like you're falling even though you're lying in bed? Babies feel this in utero (starting in the third trimester) when a mom's sudden movement causes them to fling out their arms and legs reflexively. This startle reflex continues after birth, and some parents may confuse the reflex with seizures because it's often accompanied by trembling.
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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.