Fetal Development

The first step to conceiving a baby is fertilizing a biological female’s egg. This egg is fertilized by a sperm cell, which would come from a biological male. When the sperm and egg meet, we now have a zygote! This zygote has all the DNA needed for the baby, both from the mother and the father. As this zygote travels down the woman’s fallopian tube, on its way to the uterus, it starts replicating and dividing, resulting in a blastocyst. Essentially, the inner cells inside the blastocyst will develop into an embryo, and the outer shell will protect it and help it grow. At around week 4, the blastocyst will reach the uterus, where the cell will go on to develop. The blastocyst is located in the uterus so it can be nourished by the mother’s blood, making it the perfect place for development. At around week 5, the cell is now considered an embryo. This is where the cells duplicate, but instead of all being the same, they “differentiate”, meaning different cells will now grow into cells with different purposes. Some cells will turn into blood cells, others will be kidney cells, etc. Vital organs will also start to develop, such as the heart, brain, and spinal cord.

Due to the importance of this stage, this is where the baby is also at a lot of risks. The mother’s behavior, such as drinking, eating unhealthy, or taking specific medicines, can heavily impact the baby’s growth.From week 6 to 8, more and more of the baby starts to grow, such as the arms and the legs. Usually, at this time, you can even see the heartbeat! At week 9, hair follicles start to grow, along with toes, elbows, and ALL vital organs are being developed. From week 10-14, smaller details start to become more noticeable, such as facial features, nails, teeth, and hands. During weeks 15 to 21, bones and tissue are strengthened, and the baby can start moving. The baby also starts to hear, pump its fists, and can even swallow at the end of this period. During weeks 22-25, the baby develops facial hair and moves a lot more. Because it is swallowing a lot more, the baby also starts to accumulate fat. From week 26-30, the baby is forming air sacs in the lungs and is readying itself to breathe outside the womb. It can also hear loud noises and will have the ability to react to them. Lastly, because the brain and nervous system are developing, the baby will have control over some movements and limbs. From weeks 31-37, the baby starts storing a lot of fat and gains weight, alongside storing vital nutrients, such as calcium and iron. At the end of week 37, all muscles and bones are developed to the max, along with the heart and blood vessels, meaning it can breathe sustainably! From weeks 38-40, the baby is ready to come out of the uterus and could be born anytime. Preemies: A preemie is a baby born 37 weeks after conception, usually meaning it is not fully developed. Around 1 baby in every 10 babies is born a preemie, making it somewhat common. Preemies are usually a lot smaller, as they have not stored as much fat and nutrients. Because of this, preemies are placed in a NICU, where they are supplied with oxygen and other substances to help their organs run. Even though they face struggles, with current technology, there is almost a 100 percent survival rate with babies born in the 34-36 week timeline. That’s amazing! ​ Genetic Disorders: While it would be amazing if all children were born healthy with their bodies functioning, many babies are born with defects. This happens because of issues during the baby’s development in the womb. Here are some of them, and why they occur: Single Gene Disorders: Sometimes a single gene can cause a disease, such as cystic fibrosis or hemophilia. Chromosomal Abnormalities: This is when there is an extra pair of chromosomes or less than normal, and usually causes down syndrome. Multifactorial or Complex Disorders: These types of disorders are caused by environmental factors, such as the mother’s diet or harsh conditions, and usually can’t be traced down to simply one cause. This can result in heart defects or spina bifida. Teratogenic Disorders: These disorders are caused by substances that the embryo is exposed to during its development stages, such as drugs and medicines, and can lead to abnormalities, or “teratogens.” Sources: https://medlineplus.gov/ency/article/002398.htm#:~:text=Gestation%20is%20the%20period%20of,It%20is%20measured%20in%20weeks. https://medlineplus.gov/prematurebabies.html https://women.texaschildrens.org/program/high-risk-pregnancy-care/conditions/genetic-disorders#:~:text=Examples%20include%20heart%20defects%2C%20cleft,of%20the%20organs%20are%20developing.