Your pregnancy calendar is a 40 week period. However you are not really pregnant until week three. That is because your due date is determined by your last menstrual period. Women typically deliver 40 weeks after their last menstrual period (LMP), but are not pregnant until two weeks after their LMP. When you have your menstrual period, it will be two weeks before you ovulate and release another egg that can be fertilized by your husband or partners sperm. So this conception takes place two weeks after your LMP and the first week of pregnancy is actually the third week after your LMP. Therefore, although we talk about the 40 weeks of pregnancy your baby develops over 38 weeks but you deliver 40 weeks after your LMP.In the first week after your LMP nothing has really changed. It is a normal week for you. You are not pregnant. You just had your period, you diuresed (which means to urinate the fluid you retained during your period). Perhaps you have lost a pound or two from this. Hopefully, you have a regular exercise plan, you eat healthy and you are getting regular sleep. Having a baby at this point is just a twinkle in you and your lover’s eyes.
Your ovaries are the source of all your eggs. Each month, between periods, one or more eggs are released. The egg that has been released can only be fertilized for only 24 hours; it is at this point that you are most likely to get pregnant if you have sex.
This is conception week and will mark the beginning of your baby and its prenatal development. The egg is fertilized by the sperm in the fallopian tube. Once the egg is fertilized, a hormone that is called human chorionic gonadotropin (HCG) is produced and this prevents further menstrual periods and keeps your ovaries from ovulating again during this pregnancy. The fertilized egg is given a series of names as it travels down the fallopian tube to the uterus and begins to grow. First it is a zygote, this is only two cells, and then it is a small cluster of multiple cells called a blastomere. When it reaches the uterus six days after conception it is about 100 cells and is called a blastocyst. This marks the end of week three. Women do yet realize they are pregnant. There are no obvious changes to your body either physically or emotionally.
During this week the blastocyst will implant in uterus. This usually takes place between days 23 through 26. The blastocyst will develop into the placenta and baby. The blastocyst is very tiny but can be seen with the naked eye. It is a little bigger than the period at the end of this sentence. Two rapid developments are going on. The placenta is the organ between the uterus and the developing baby that provides nourishment. By definition, during the first ten weeks the developing baby is called an embryo and after that it is called a fetus.A mucus plug forms in your cervix at this time. The cervix is the opening between the vagina and uterus. The mucus plug will help keep the uterus free of any bacteria or infections. Organ formation is already taking place very rapidly. Cell layers that develop into the heart and nervous system need support from proper nutrition. Especially important is folic acid which helps reduce the risk of spina bifida and congenital heart disease. Young women need to eat foods high in folic acid during their child bearing years like spinach, cabbage, broccoli and dark green leafy vegetables in general. Also look for foods that say they are fortified with folic acid and build them into your diet. Also important is what not to eat. Read labels!!!The hormones estrogen and progesterone now start to increase dramatically. They prepare your body in many ways and will be a source of many of the symptoms of pregnancy, from morning sickness to weight gain.