Week 18-20 An ultrasound will be offered. The second trimester maternal serum screening will be offered at this time if the first trimester test was not done (see week 12). Eyelashes and eyebrows have appeared, and the tongue has tastebuds. Week 16The fetus is around 14 cm in length. The baby can now mutely cry, since it has vocal cords. Week 14 The eyelids are fused over the fully developed eyes. Week 13 The fetus can swim about quite vigorously. This test checks for trisomy 18 (Edward syndrome) and trisomy 21 (Down syndrome). The first trimester combined screening test (maternal blood test + ultrasound of baby) can be done around this time. Week 12 The fingers and toes are recognisable, but still stuck together with webs of skin. Week 11 Teeth are budding inside the gums. The hands and feet, which previously looked like nubs or paddles, are now evolving fingers and toes. Week 10 The embryo is now known as a fetus and is about 2.5 cm in length. Blood cells are being made by the embryo’s liver. The tiny muscles allow the embryo to start moving about. Week 9 The eyes, mouth and tongue are forming. The rapidly growing spinal cord looks like a tail.
Week 8 The embryo is now around 1.3 cm in length. The placenta is burrowing into the uterine wall to access oxygen and nutrients from the mother’s bloodstream. The embryo has developed its placenta and amniotic sac. By this stage, it is secreting special hormones that prevent the mother from having a menstrual period. Week 6 The baby is now known as an embryo. Week 5 The evolving neural tube will eventually become the central nervous system (brain and spinal cord). The rapidly dividing cells are in the process of forming the various body systems, including the digestive system. Week 4 The developing baby is tinier than a grain of rice. Seven days after conception, the zygote burrows itself into the plump uterine lining (endometrium). After two more days, the zygote has migrated from the fallopian tube to the uterus (womb). Three days later, the cell (zygote) has divided into 16 cells. Week 3 Thirty hours after conception, the cell splits into two. Week 2Fertilisation of your egg by the sperm will take place near the end of this week. Because your expected birth date (EDD or EDB) is calculated from the first day of your last period, this week counts as part of your 40-week pregnancy, even though your baby hasn’t been conceived yet.
Week 1 This first week is actually your menstrual period. The gender and inherited characteristics are decided in that instant. First trimester – conception to 12 weeksĬonceptionThe moment of conception is when the woman’s ovum (egg) is fertilised by the man’s sperm.Pregnancy is divided into three trimesters: This is because pregnancy is counted from the first day of the woman’s last period, not the date of conception, which generally occurs two weeks later. The unborn baby spends around 38 weeks in the womb, but the average length of pregnancy (gestation) is counted as 40 weeks.