Pregnancy timeline

Pregnancy timeline

Weeks 1-4

Fertilisation occurs and a ball of quickly multiplying cells embeds itself in the lining of the uterus. In the UK pregnancy is calculated from the first day of the woman's last period so for as much as three weeks of this first month she might not be actually pregnant. When fertilisation does occur the tiny mass of cells called a blastocyst at this stage embeds itself in the lining of the womb which is already thickening to support it. Week 5 The mass of cells is developing fast and becomes an embryo. For many women the first sign of pregnancy is a missed period. Shopbought tests are considered largely reliable so the mother-to-be does not have to have her pregnancy confirmed by her GP. If a first test is negative a second one a few days later may prove positive as hormone levels in the urine rise. Week 6 The embryo officially becomes a foetus. It is about the size of a baked bean and its spine and nervous system begin to form. The foetus already has its own blood system and may be a different blood group from its mother. Blood vessels are forming in what will become the umbilical cord and tiny buds which will become limbs appear. Week 7 The baby´s heart is beginning to develop. Morning sickness and other side effects of early pregnancy may take hold. Around this time many women find they experience the side-effects of early pregnancy including needing to urinate more often nausea and vomiting and feeling a bit weepy and irritable. All medication including supplements need to be carefully checked as the foetus is undergoing vital development in the first 12 weeks. If the woman has not told her GP or community midwife she is pregnant yet now is a good time to do so. Week 8 It is quite common to have a first scan at this stage if the woman has had a previous miscarriage or bleeding. An early scan is often done through the vagina and is used to check the pregnancy is not ectopic. It should show up the baby´s heartbeat. The nervous system is also developing rapidly especially the brain. The head gets bigger and eyes form under the skin of the face. The foetus' limbs are growing and look more like arms and legs. All internal organs are developing and becoming more complex. Week 9 Women who may be at higher risk of passing on sickle cell anaemia and thalassaemia should be offered a blood test before 10 weeks. These conditions are rare but serious inherited blood disorders. They are more common in people of certain ethnic backgrounds including African, Caribbean and some Asian and Mediterranean communities. If the mother is found to carry the gene for either condition, the father is offered a test. If both parents are found to be carriers then they are offered the option of testing the foetus in the womb. Week 10 A scan at 10-13 weeks is recommended to pin down the date of the pregnancy. Week 11 The umbilical cord is fully formed providing nourishment and removing waste products. The foetus looks fully human now. Week 12 By this week the threat of miscarriage is much reduced. Many women announce their pregnancy to friends and colleagues. The foetus is growing in length much more quickly by now it is about eight cm long and weighs about 60 grams. The placenta is now wellformed though it's not yet doing its full job it takes over fully in week 14. The mother is likely to have her first scan this week. Week 13 The woman uterus is becoming larger and is starting to rise out of the pelvis. The foetus can move its head quite easily.