Authored by Revere Health

Pregnancy Milestones by Trimester

November 30, 2017 | Women and Children's Center

A woman reaches several milestones throughout her pregnancy, and they differ for every trimester. Here’s a look at what milestones you can expect both during and post-pregnancy.


First Trimester

During the first three months of pregnancy, your baby’s basic organ system begins to develop. You’ll be tired more often, and will likely have to use the bathroom more often. Some pregnant women also experience constipation. Some milestones you may hit include:

  • •4 weeks: A ball of cells called a blastocyst has officially become an embryo, roughly the size of a poppy seed. This is when organ development begins, lasting approximately six weeks.
  • •5 weeks: The baby’s heart begins to beat, generally at about twice the rate of an adult heart.
  • •6 weeks: Facial features begin to form, and little buds for the arms and legs start to develop.
  • •10 weeks: The embryo officially becomes a fetus. Organs like kidneys, intestines, brain, and liver are beginning to function, and fingernails and toenails are starting to form.
  • •12 weeks: You’ll likely be able to hear the baby’s heartbeat at a prenatal checkup, though this may have already happened at an ultrasound.

Second Trimester

By the beginning of the second trimester, many mothers feel more energetic and have less nausea—though some experience more headaches. It’s important to stay hydrated during this period. Certain milestones include:

  • •14 weeks: The baby’s kidneys are producing urine that’s released into the amniotic fluid. The baby can make facial expressions and may begin sucking his or her thumb.
  • •16 weeks: The baby’s gender might be detectable at a mid-pregnancy ultrasound, which is generally done between 16 and 20 weeks into pregnancy.
  • •18 weeks: If you haven’t already felt the baby moving around in the womb, you likely will around this time. Within a couple weeks after that, other people should be able to feel baby movements from outside your stomach.
  • •23 weeks: The baby’s sense of motion has developed, and hearing continues to improve.
  • •24 weeks: taste buds are developing, and both the brain and hair should be growing quickly. The baby may weigh just over a pound and be up to a foot long.
  • •27 weeks: Though they won’t be functional for a few more weeks, the baby’s lungs are developing quickly. The baby will inhale and exhale amniotic fluid and will have begun sleeping and waking at regular intervals. They’ll also likely begin opening and closing their eyes and sucking on their fingers


Third Trimester

Try to stay active during the third trimester. You may feel some tightness in the uterus (Braxton-Hicks contractions), that are preparations in the uterus for labor. You’ll have more regular check-ups to avoid complications. Other milestones include:

  • •28-32 weeks: The baby may begin dreaming, and will have eyelashes and improved eyesight. The baby will also grow fingernails and toenails and may begin to increase in weight—up to over three pounds, and nearly four.
  • •34 weeks: The baby’s lungs and central nervous system continue to develop, and skin is becoming soft and smooth.
  • •37 weeks: At this point, your baby is considered “early term.” Babies born at this time usually do well, but in an ideal situation, birth won’t take place for a few more weeks to allow the brain and lungs time to mature fully.
  • •39 weeks: The baby is now considered full-term, and is ready for birth. Average weight is roughly 7.5 pounds, and the average length is about 20 inches.
  • •41 weeks: You’ve passed your due date, and the baby is now considered “late term.” Anything after 42 weeks is “post-term.” Baby health might be monitored with tests, and you may discuss inducing labor with your doctor to avoid complications.

After Pregnancy

Some women call the period after pregnancy the “fourth trimester,” and it’s vital to keep taking care of yourself during this period despite most of your focus naturally being on the baby. Take offers from friends and family to help, and ensure you get enough rest. Don’t worry about normal tasks like cleaning—focus on the baby and yourself.

Your doctor can offer more information on common pregnancy milestones.


Revere Health Imaging offers the most advanced imaging technology in Utah Valley with convenient locations and reduced-cost exams. We even offer our imaging services at night for your convenience. Contact us today at 801-812-4624 for an appointment!



“Pregnancy Milestones: Pregnancy by Trimester.”

“Fetal development timeline.”


The Live Better Team

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This information is not intended to replace the advice of a medical professional. You should always consult your doctor before making decisions about your health.