My husband and I had been trying to conceive for almost a year. I was delighted when my menstrual cycle was late. My husband, ever cautious, took a wait-and-see attitude.
After a few days had passed without my menstrual cycle starting, I bought a home pregnancy test. My husband waited in the living room while I took the test that would tell us whether we were parents-to-be. Sure enough, a faint blue line appeared on the test. I showed it to my husband, who said excitedly, "It's a maybe?"
No maybe about it. We were expecting our first child.
-- One couple's experience
Your baby's growth during weeks 1 to 4
If you're like most expectant parents, your mind is full of questions. What does my baby look like right now? How big is he or she? How is she or he changing this week? Becoming familiar with how your baby develops, week by week, will help you answer some of those questions. It may also help you understand some of the changes taking place in your body.
Weeks 1 and 2: Preconception and fertilization
Preconception
It may seem a bit strange, but the first week of your pregnancy is actually your last menstrual period before becoming pregnant. Why is that? Doctors and other health care professionals calculate your due date by counting 40 weeks from the start of your last cycle. That means they count your period as part of your pregnancy, even though your baby hasn't been conceived yet.
Conception typically occurs about two weeks after the start of your last menstrual period. When your baby arrives, it will have been about 38 weeks since he or she was conceived, but your pregnancy will have "officially" lasted 40 weeks.
Even while menstruation is happening, your body begins producing a hormone called follicle-stimulating hormone, which fosters development of an egg in your ovary. The egg matures within a small cavity in your ovary called a follicle. A few days later, your body produces a hormone called luteinizing hormone. It causes the follicle to swell and burst through the wall of your ovary, releasing the egg. This is called ovulation. You have two ovaries, but in any given cycle, ovulation occurs from just one of them.
The egg moves slowly into your fallopian tube, which connects your ovary and uterus. There it awaits a fertilizing sperm. Finger-like structures at the junction between your ovary and fallopian tube, called fimbriae, catch the egg when ovulation occurs, keeping it on the right course.
If you have intercourse before or during this time, you can become pregnant. If fertilization doesn't occur, for whatever reason, the egg and the lining of your uterus will be shed through your menstrual period.
Fertilization
This is when it all begins. Your egg and your partner's sperm unite to form a single cell -- the starting point for an extraordinary chain of events. That microscopic cell will divide again and again. In about 38 weeks, it will have grown into a new person made up of more than 2 trillion cells -- your beautiful new baby girl or boy.
The process begins when you and your partner have sexual intercourse. When he ejaculates, your partner releases into your vagina semen containing up to 1 billion sperm cells. Each sperm has a long, whip-like tail that propels it toward your egg.
Hundreds of millions of these sperm swim up through your reproductive system. With the help of your uterus and fallopian tubes, they travel from your vagina, up through the lower opening of your uterus (cervix), through your uterus and into your fallopian tube. Many sperm are lost along the way. Only a fraction of the sperm reach the egg's position in the fallopian tube.
...clear and compassionate answers to many of the questions and decisions that parents often encounter.
As a specialist in obstetrics and gynecology at Mayo Clinic, Roger W. Harms, M.D., has guided thousands of women through pregnancy and childbirth. Throughout each pregnancy, his goal is to help parents-to-be make informed decisions that meet their personal values during the journey toward parenthood.
Teaching is Dr. Harms' other passion. He has served as associate dean for academic affairs at Mayo Clinic College of Medicine and has received the Association of Professors of Gynecology and Obstetrics "Excellence in Teaching" award. As medical director of the reproductive health center for MayoClinic.com, Dr. Harms has been a leader in parent education. Dr. Harms acknowledges fatherhood as his greatest learning experience.
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