Share on Pinterest
Evil Pixels Photography/Stocksy United

Pregnancy is an exciting time full of rapid change and development for both you and your baby. While the growth happening on the outside is clear to everyone (hello, growing belly!), it’s the development we can’t see that is truly fascinating.

Your fetus will begin the process of developing a brain around week 5, but it isn’t until week 6 or 7 when the neural tube closes and the brain separates into three parts, that the real fun begins.

Around week 5, your baby’s brain, spinal cord, and heart begin to develop. Your baby’s brain is part of the central nervous system, which also houses the spinal cord. There are three key components of a baby’s brain to consider. These include:

  • Cerebrum: Thinking, remembering, and feeling occurs in this part of the brain.
  • Cerebellum: This part of the brain is responsible for motor control, which allows the baby to move their arms and legs, among other things.
  • Brain stem: Keeping the body alive is the primary role of the brain stem. This includes breathing, heartbeat, and blood pressure.

The first trimester is a time of rapid development and separation of the various parts of the brain, according to Kecia Gaither, MD, MPH, double board certified in obstetrics and gynecology and maternal-fetal medicine, and director of perinatal services at NYC Health + Hospitals/Lincoln.

Within 4 weeks, the rudimentary structure known as the neural plate develops, which Gaither says is considered the precursor to the nervous system. “This plate elongates and folds on itself forming the neural tube — the cephalad portion of the tube becomes the brain, while the caudal portion elongates to eventually become the spinal cord,” she explains.

The neural tube continues to grow, but around week 6 or 7, Gaither says it closes, and the cephalad portion (aka the rudimentary brain) separates into three distinct parts: front brain, midbrain, and hindbrain.

It’s also during this time that neurons and synapses (connections) begin to develop in the spinal cord. These early connections allow the fetus to make its first movements.

During the second trimester, Gaither says the brain begins to take command of bodily functions. This includes specific movements that come from the hindbrain, and more specifically, the cerebellum.

One of the first notable developments, sucking and swallowing, are detectable around 16 weeks. Fast-forward to 21 weeks, and Gaither says baby can swallow amniotic fluid.

It’s also during the second trimester that breathing movements begin as directed by the developing central nervous system. Experts call this “practice breathing” since the brain (and more specifically, the brain stem) is directing the diaphragm and chest muscles to contract.

And don’t be surprised if you feel some kicking during this trimester. Remember the cerebellum or the part of the brain responsible for motor control? Well, its directing the baby’s movements, including kicking and stretching.

Gaither points out that a fetus can begin to hear during the late second trimester, and a sleep pattern emerges as the brainwaves from the developing hypothalamus become more mature.

By the end of the second trimester, Gaither says the fetal brain looks structurally much like the adult brain with the brain stem almost entirely developed.

The third trimester is full of rapid growth. In fact, as your baby continues to grow, so does the brain. “All the convoluted surfaces of the brain materialize, and the halves (right brain and left brain) will separate,” explains Gaither.

The most notable part of the brain during this final trimester is the cerebellum — hence, the kicking, punching, wiggling, stretching, and all of the other movements your baby is performing.

Share on Pinterest
Illustration by Alyssa Kiefer

While it may feel like you have control over nothing for the next 9 months, you do have a say in the foods you eat. Healthy brain development starts before pregnancy.

According to the Centers for Disease Control and Prevention, a healthy diet that includes folic acid, both from foods and dietary supplements, can promote a healthy nervous system.

“There are a number of defects along the baby’s brain and spinal cord that can occur when there is an abnormality occurring within the first weeks of brain development,” says Gaither. This may include anencephaly or spina bifida.

Gaither says two supplements in particular are involved with fetal brain development:

Folic acid

Folic acid (vitamin B9, specifically) supports fetal brain and spinal development. Not only does it play a role forming the neural tube, but Gaither says it’s also involved in the production of DNA and neurotransmitters, and it’s important for the production of energy and red blood cells.

Gaither recommends taking at least 400 to 600 micrograms of folic acid daily while you’re trying to conceive, and then continue with 400 micrograms daily during pregnancy.

“If you’ve had a child with a neural tube defect, then 4 grams daily in the preconceptual period is advised,” says Gaither.

Foods rich in folate/folic acid include dark green leafy vegetables, flaxseed, and whole grains.

Omega-3 fatty acids

Also important for fetal brain development are omega-3 fatty acids. “The brain has a high fat content, and the omegas are helpful in the deposition of the fat in not only the brain, but the eyes as well,” explains Gaither.

Omegas are also helpful in the neural synapse development or nerve connections to each other.

Foods rich in omega 3-fatty acids include salmon, walnuts, and avocados.

Fetal brain development starts before you may even realize you’re pregnant. That’s why it’s important to start on a prenatal vitamin that contains folic acid right away. If you’re not pregnant, but thinking about having a baby, add a prenatal vitamin to your daily routine.

The brain begins to form early in the first trimester and continues until you give birth. During pregnancy, fetal brain development will be responsible for certain actions like breathing, kicking, and the heartbeat.

Talk to your doctor if you have any questions about your pregnancy, fetal brain development, or how to nurture the baby’s developing brain.