Pregnancy

Brain development of the fetus during pregnancy

The brain begins forming in the early first trimester and continues to grow and specialize. During pregnancy, the developing fetal brain will be responsible for certain actions such as breathing, kicking and heartbeat.

Pregnancy, we will never stop stressing it, is a period of enormous changes that affect the woman and the child she is carrying. If from the outside we can all see the increase in the baby bump, it is what happens inside it that is extremely fascinating.

The development from a single fertilized cell, to embryo to fetus, is an extraordinary journey . In the first weeks, starting from the moment in which the sperm meets the oocyte to give rise to the zygote, there is a frenetic succession of specializations and differentiations .

The process of developing a brain begins around 5 weeks of pregnancy, but it’s only between 6 and 7, when the neural tube closes and the brain separates into three parts, that the real process begins.

What are these three parts?

The baby’s brain is part of the central nervous system, which also includes the spinal cord. There are three key components of a child’s brain which are:

  • Brain : this is where thoughts, memories and sensations come to life.
  • Cerebellum : This part of the brain is responsible for motor control, which allows the baby to move their arms and legs, among other things
  • Brainstem : The main and fundamental role of this part is to keep the body alive . Its monitoring functions include breathing, heart rate and blood pressure, among others.

Brain development in the first trimester of pregnancy

The first trimester is a time of rapid development and differentiation of various parts of the brain. Within 4 weeks, the rudimentary structure known as the neural plate develops , which is considered the precursor to the nervous system. This plate stretches and folds back on itself, forming the neural tube: the cephalic portion of the tube becomes the brain, while the caudal portion elongates to become the spinal cord.

The neural tube continues to grow, but between 6-7 weeks of pregnancy, it closes, and the cephalic portion (i.e. the rudimentary brain) separates into distinct parts: telencephalon, diencephalon, midbrain, metencephalon, myelencephalon, and the spinal cord.

It is around this time that neurons and synapses (connections) begin to develop in the spinal cord. These first connections allow the fetus to make its first movements .

Brain development in the second trimester of pregnancy

During the second trimester, the brain begins to take over bodily functions.   These functions also include the specific movements that come from the cerebellum.

Already around 16 weeks of pregnancy two notable functions appear which are sucking and swallowing . Around the  21st week of pregnancy, the baby can swallow amniotic fluid.

In the second trimester, the ” breathing exercises ” also begin, the brainstem begins to direct the activities of the diaphragm and chest muscles.

The second quarter is also where the first kicks begin to feel . These movements are directed by the cerebellum, the part of the brain responsible for motor control.

A fetus can begin hearing during the late second trimester. At this stage the fetal brain structurally closely resembles the adult brain with the brainstem almost fully developed.

Brain development in the third trimester of pregnancy

The third quarter is the period of growth, in every sense.

The most active part of the brain during this final trimester is the cerebellum, the fetus is in fact busy with frenetic activities: kicks, punches, stretching .. , an infinity of movements that can be well seen during a 4D ultrasound .

How can we help the developing brain of the fetus

It is not true that we have no control over the growth of the baby during pregnancy .

The health of the fetus and newborn depends a lot on our lifestyle before and during pregnancy. In particular, with regard to brain development, it is recommended that women take folic acid .

There are a number of defects (including spina bifida and anencephaly) that can affect a child’s brain and spinal cord. They are caused by abnormalities that occur within the first few weeks of development.

To prevent them, folic acid helps us. The dose and type of folate to be taken depends on the condition of the woman, on any MTHFR mutations , or on previous pregnancies with the presence of complications of this type. For this reason it is always good to consult with the specialist.

Under normal conditions, the recommended supplementation is 0.4 mg of folic acid per day to be taken preferably starting from the three months preceding the beginning of the search for pregnancy.

Folate-rich foods include dark leafy greens, flaxseeds, and whole grains.

In addition to folate, omega-3 fatty acids are also important for fetal brain development.

The human brain is composed predominantly of lipids: phospholipids that make up 22% of the cerebral cortex and 24% of the white matter.

In the third trimester of pregnancy, omega-3 fatty acids are selectively transferred to the fetus to meet the needs of rapid brain growth, and DHA accumulates in the fetal brain at a rate of 14.5mg/week.

DHA is the predominant fatty acid found in the brain, although the proportion of DHA varies by brain region.

DHA has been shown to support neuronal proliferation and reduce apoptosis of neurons.

The brains of babies born before 33 weeks of gestation were found to be relatively deficient in DHA compared to the brains of full-term babies, a finding that may explain some of the subtle developmental abnormalities seen in babies born prematurely.

Due to the importance of DHA in brain structure, it has been hypothesized that the relative imbalance of omega-6 and omega-3 fatty acids in the modern diet may have negative consequences on development.

Many pregnant women avoid fish in pregnancy, for fear of pollutants, but fish is the main source of omega-3 fats . This concern, combined with a Western diet relatively deficient in omega-3 fatty acids, has created an imbalance of omega-3 versus omega-6 fats. This imbalance can lead to a proinflammatory state that contributes to a number of complications, including preterm birth, hypertension in pregnancy, and postpartum depression. Fetal omega-3 fat deficiency can put newborns at risk for allergic disease and suboptimal neuropsychiatric development.

Are supplements needed? Studies on the risks and benefits of Omega-3 supplementation in pregnancy are conflicting. Therefore, further studies on the topic are needed. for any doubts, it is recommended to consult your doctor.

Dr Kathryn Barlow

Kathryn Barlow is an OB/GYN doctor, which is the medical specialty that deals with the care of women's reproductive health, including pregnancy and childbirth.

Obstetricians provide care to women during pregnancy, labor, and delivery, while gynecologists focus on the health of the female reproductive system, including the ovaries, uterus, vagina, and breasts. OB/GYN doctors are trained to provide medical and surgical care for a wide range of conditions related to women's reproductive health.

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