An Overview of Your Baby’s Development by Trimester


From conception to birth, a baby must hit many major milestones before he or she is ready to come in to this world, and it is fun to know when they should happen. Here is a look at some of the biggest happenings throughout each trimester of pregnancy.

First Trimester: 1 to 12 Weeks

During this time, your baby goes from microscopic size to over 2 inches long. At 5 weeks, your baby's heart begins to beat at a rate twice as fast as yours! At 10 weeks, the vital organs are formed and begin to function, including the brain, intestines, liver, and kidneys. By the end of the first trimester, your baby is almost fully formed!

Second Trimester: 13 to 27 Weeks

Your baby's gender is distinguishable through an ultrasound as early as around 13 weeks, but your doctor will usually wait to perform the gender ultrasound until between 16 and 20 weeks. Your baby can see light from outside the womb and begin to hear sounds as well during the second trimester. You are likely to start feel him or her moving sometime around 20 weeks.

Third Trimester: 28 to 40 Weeks

Early in the third trimester, his or her face is nearly completely formed, including eyelashes! By 32 weeks your baby will also have finger and toenails. At 37 weeks, your baby is officially considered full-term, although his or her lungs will become even more developed in the next couple of weeks.

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