Know your pregnancy milestones
We take a look at how your baby develops in utero at different stages in your pregnancy.
Pregnancy is an exciting time. Each week, your baby grows and develops in new ways, changing from a blastocyst in the very first stage of pregnancy, to an embryo and then a foetus. Read on to find out more about your little one’s development before they are even born…
The very beginning
The first key stage in your baby’s development is fertilisation, says Rosemary Byrnes, a registered nurse based in George. After an egg is fertilised, it will begin to divide into multiple cells as it moves from the fallopian tubes and into the uterus. When the egg enters the uterus, it will burrow into the uterine lining and rapidly multiply into a ball of cells known as a blastocyst. At around four weeks, a blastocyst becomes a tiny embryo, around the size of a poppy seed.
Over the course of the next few weeks, a number of significant developments occur. At around five weeks, a circulatory system begins to form; and at six weeks a nose, mouth, ears, intestines and brain all start to develop.
Time for an appointment
By 10 weeks, your embryo’s most critical development has taken place. “It’s best to have your first antenatal visit before 10 weeks,” advises Byrnes. “At this point, your baby is considered a foetus.”
Week 13 marks the last week of the first trimester, and at 14 weeks, Byrnes says that your little one’s sex can usually be identified. “Most women start to feel some movement between 16 and 20 weeks,” she says. At this point, the umbilical cord strengthens and your baby’s senses are rapidly developing. By 20 weeks, your baby is able to swallow and their digestive system produces a substance known as meconium, which will be passed in their first stool.
“At 24 weeks, a baby can survive outside the uterus,” says Rosemary. From this point, your little one becomes chubbier over time. By 26 weeks, your baby starts to inhale and exhale amniotic fluid, which helps with lung development.
The last trimester
Week 28 marks the beginning of the third trimester, and baby takes up more and more space for the last stretch of pregnancy. During this trimester, your baby’s eyesight develops, the head continues to grow, and a protective layer of fat develops under the skin. “The lungs mature towards the end of pregnancy, while the brain develops throughout pregnancy,” says Rosemary.
By 35 weeks, your baby’s kidneys have fully developed and the liver is capable of processing waste. Although your baby has grown considerably, they are only considered full-term at 39 weeks when their physical development is complete. During the time your baby spends in the womb after this point, they will continue to put on weight as they get ready for birth.
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