Fertilization: A Sperm and an Egg Form a Zygote When a sperm cell penetrates and fertilizes an egg, that genetic information combines. The 23 chromosomes from the sperm pair with 23 chromosomes in the egg, forming a 46-chromosome cell called a zygote. The zygote starts to divide and multiply.

When a Zygote Becomes an Embryo Zygotes divide through a process known as mitosis, in which each cell doubles (one cell becomes two, two becomes four, and so on). The zygote then travels down the fallopian tube to the uterus. As it travels, its cells rapidly divide and it becomes a blastocyst.

Blood cells, kidney cells, and nerve cells all develop. The embryo grows rapidly, and the baby’s external features begin to form. Your baby’s brain, spinal cord, and heart begin to develop. Baby’s gastrointestinal tract starts to form.

Development of the Fetus and Placenta. At the end of the 8th week after fertilization (10 weeks of pregnancy), the embryo is considered a fetus.

Three Months Pregnant: Your Body’s Changes It’s possible that you might start to project a small baby bump sometime soon, although every mom-to-be starts to show at different times. By this month, your uterus has grown to about the size of a large orange.

Growth of the Uterus Shortly after conception – and weeks before you see an actual bulge in your stomach — your uterus begins expanding to accommodate your growing fetus. Nestled among the bones of your pelvis, your uterus is approximately the size of a fist before pregnancy.

You should wait to take a pregnancy test until the week after your missed period for the most accurate result. If you don’t want to wait until you’ve missed your period, you should wait at least one to two weeks after you had sex. If you are pregnant, your body needs time to develop detectable levels of HCG.

Most first-time mums don’t start showing until at least week 12. However, if this isn’t your first baby, then you may start showing sooner, as the muscles in your uterus (womb) and belly may have been stretched from your last pregnancy.

You at 4 weeks pregnant The fertilised egg moves down your fallopian tube to the uterus, where it implants itself in the endometrium. This can take 3-10 days. Some women have a small amount of bleeding – or ‘spotting’ – around the time of implantation.

This week, a few pregnancy symptoms may appear, though some moms-to-be won’t have noticed any signs yet. You might feel some cramping and see a little bit of spotting, both of which can happen as the fertilized egg implants itself in your uterus. Your body is now starting to make the pregnancy hormone hCG.

The Size of the Embryo at 5 Weeks Pregnant At five weeks the embryo is still very small but growing quickly! Picture a small orange seed or a grain of rice. At this stage, your little one could be between 0.05 and 0.10 inches long, with a shape similar to that of a tiny tadpole.

Baby flutters during early pregnancy You’ll likely start to feel your baby moving around sometime between weeks 18 and 20 of your pregnancy. First-time moms may not feel baby move until closer to 25 weeks. Seasoned moms may feel movement as early as 13 weeks.

The baby’s nervous system is already developing, and the foundations for its major organs are in place. At this stage, the embryo is around 2mm long. The heart is forming as a simple tube-like structure.