Having a baby and feeling a new life developing inside your womb is a wonderful journey full of emotions, changes, enrichment and challenges.
During this period, your body will undergo major physiologic and psychological changes that support maternal adaptations to prepare for the birth process and transition to parenthood.
Simultaneously, the embryo and fetus are developing from a single cell to a complex organism: a unique human life begins.
The prenatal period, from conception to birth is divided into three trimesters: from week 1 to 12, from week 13 to 26, and from week 27 to birth.
A full-term pregnancy lasts about 40 weeks, counting from the first day of the last menstrual period, which is about two weeks before conception occurs.
During each trimester, distinct changes take place in your body as well as in the development of the fetus.
Pregnancy can be different from woman to woman and even for the same mother from one pregnancy to the next. Each one is affected differently and experiences new and particular feelings.
Some pregnancy symptoms last for several weeks or months, while other discomforts are temporary or don’t affect the expecting mother at all.
The baby will develop inside the uterus with the help of a fetal life support system composed of the placenta, the umbilical cord and the amniotic sac.
At the beginning, the lining of your uterus thickens and its blood vessels enlarge to provide nourishments to the fetus. As pregnancy progresses, the uterus expands to make room for the growing baby. By the time the baby is born, the uterus will have expanded to many times its normal size.
The placenta is a specialized organ that supports the normal growth and development of the fetus. Its function is to ensure the exchange of nutrients and waste products between the maternal and fetal circulatory systems. Oxygen, nutrients and hormones from the mother are transferred across the placenta to reach the baby. Waste products from the baby, such as carbon dioxide are transferred to the mother for removal.
The placenta can also help to protect the fetus against certain infections and maternal diseases.
The umbilical cord is the life-line that attaches the placenta to the fetus. It is made up of three blood vessels: two small arteries which carry blood to the placenta and a larger vein which returns blood to the fetus. It can grow to be 60 cm long, allowing the baby to safely move around without causing damage to the cord or the placenta.
The amniotic sac is filled with amniotic fluid. It is the baby’s home and allows the fetus ample room to swim and move around which helps build muscle tone. To keep the baby cozy, the amniotic sac and fluid maintain a slightly higher temperature than the mother’s body.
Conception and implantation
About two weeks after a woman has her period, she ovulates and her ovaries release one mature egg.
Conception occurs when the sperm and egg unite in one of the fallopian tubes to form a one-celled entity called a zygote which contains 46 chromosomes, (23 from the mother and 23 from the father). These chromosomes will determine all physical characteristics of the fetus and ultimately the genetic make-up of your baby.
The sex of the fetus is already determined at fertilization, depending on whether the egg receives an X or a Y chromosome from a sperm cell. If the egg receives an X chromosome, the baby will be a girl; an Y chromosome means the baby will be a boy.
Soon after fertilization, the zygote travels down the fallopian tube towards the uterus. At the same time, it will begin dividing to form a cluster of cells in a process named cleavage. By the time it reaches the uterus, the rapidly dividing ball of cells known as a blastocyst, has separated into two sections.
The inner group of cells will become the embryo. The outer group will become the cells that nourish and protect it. On contact, the blastocyst will burrow into the uterine wall for nourishment. This process is called implantation.
Once the embryo is implanted on the uterine wall, your body begins to secrete a hormone called human chorionic gonadotrophin (hCG) which can be used in a laboratory, to detect pregnancy.
Pregnancy hormones such as oestrogen and progesterone may trigger symptoms including fatigue, tender breast or nausea, especially in the first three months.
Progesterone which is initially produced by the corpus luteum, rises throughout pregnancy and continues to do so until the birth of your baby.
In early pregnancy, progesterone is responsible for increasing uterine blood flow, establishing the placenta and stimulating the growth and nutrient of the endometrium (lining of the uterus).
Additionally, progesterone plays a vital role in fetal development, preventing premature labour and lactation, as well as strengthening the pelvic wall muscles to prepare your body for labour.
Another vital hormone in pregnancy is oestrogen, which is responsible for fetal organ development, placental growth and function and mammary gland growth, which will be important for lactation after the birth of your baby.
Pregnancy due date is calculated using the first day of the last menstrual period. Only about 1 in 20 women give birth in their exact due dates.
The estimated due date (EDD) determines your baby’s gestational age throughout the pregnancy so that the baby’s growth can be tracked. It also provides a timeline for certain tests that can be performed.
For instance, circulating fetal DNA analysis is possible from the 10th week for the early detection of chromosomal disorders including Down syndrome. During pregnancy, cell-free fragment’s of the baby’s DNA circulate in the mother’s blood. Fetal DNA is detectable from the 5th week of gestation and its concentration increases during the following weeks. The amount of fetal DNA present in the mother’s bloodstream from the 10th week of gestation is sufficient to perform a risk- free fetal DNA screening test.
To know more about this test, please visit our Tranquility product page.