Most OBs count pregnancy starting from the first day of your last period. That's because ovulation and conception are really tough to pinpoint, but the physical signs of menstruation are much easier to spot. Yes, already! Your OB will give you a more accurate estimate when you go in for your first prenatal appointment.
You and your pregnancy at 1 to 3 weeks
Pregnancy Calendar: Your Pregnancy Week-by-Week
The early days and weeks of pregnancy are the start of an exciting journey, but at this stage you may not even suspect you are pregnant! If you have a typical day menstrual cycle, one of your ovaries will release an egg around 14 days after the first day of your last period. The egg will travel down one of the fallopian tubes where it may be united with sperm. This means your window of fertility when you should have sex if you are trying to get pregnant is about five days before you ovulate to one day after.
Changes in Your Body During Pregnancy: First Trimester
View video transcript. This week the groundwork is laid for the big O — ovulation — the all important first step toward the making of the baby of your dreams. And like those dreams, the baby action is all in your head right now — where the hypothalamus, the control center in your brain, works with its partner in reproduction, the pituitary gland, to start releasing hormones. These hormones — called FSH and LH — prompt the ovaries to get cracking on some eggs, ripening one to maturity within its follicle.
Now what? A lot happens during the first trimester of your pregnancy. You also might be feeling morning—okay, all the time—sickness, and feeling really, really, really tired. During the first trimester, your baby grows from the size of a poppy seed.