The first weeks of pregnancy are a time of tremendous growth and change for the new organism that will eventually become an infant. During this time, a single fertilized cell proliferates into a complex cell ball, and unspecialized cells become determined to individual structural and functional fates within the body. During the first two weeks, however, none of this is taking place yet. Instead, the mother's body is preparing itself to nurture a fertilized egg, and changes in the uterus prepare it to serve as an infant's home for the next nine months.
Misconceptions
Pregnancy math is a bit complicated, as Heidi Murkoff and Sharon Mazel point out in their book, "What to Expect When You're Expecting." The first two weeks of pregnancy, as it's counted for purposes of determining an estimated due date, are actually the two weeks between the first day of a woman's last menstrual period and the day on which she ovulates. The day of ovulation, if sperm are present in the woman's body, is also the day of fertilization. As such, the first two weeks of pregnancy represent the time up to conception.
Function
The primary functions of the first two weeks of pregnancy are the preparation of the uterus for implantation of a fertilized egg and the preparation of an egg for ovulation. This is accomplished through the actions of several hormones. Shortly after her menstrual period, a woman's body begins to secrete hormones that cause a new egg to begin to ripen in one of her ovaries. The developing egg secretes hormones, including estrogen and progesterone, that in turn cause the lining of the uterus to proliferate and thicken, so that it can provide an implanted embryo with nourishment.
Features
The major milestone of the first two weeks of pregnancy (which are only considered weeks of pregnancy if conception ensues--otherwise, they're merely weeks of a woman's menstrual cycle) is ovulation, which takes place at the end of the second week. Ovulation, the release of a ripe egg into the fallopian tube, is caused by a sharp increase in the concentration of the hormone LH. The tissue that encased the egg in the ovary, which is left behind upon ovulation, becomes an important source of hormones for the next two weeks. This tissue is called the corpus luteum, and it serves to maintain the lining of the uterus until implantation occurs.
Considerations
If a woman is trying to conceive, it's worthwhile to start making the changes to diet and lifestyle that she'll need to make in pregnancy even before conception occurs, notes Dr. Miriam Stoppard in her book, "Conception, Pregnancy and Birth." Though no baby exists yet during the first two weeks, a woman's body is nevertheless preparing itself for the tremendous task of pregnancy, and proper nutrition helps it to do so as efficiently as possible.
Expert Insight
Dr. Stoppard also notes that, to ensure that the two weeks between menstruation and ovulation become the first two weeks of pregnancy, it's best to have unprotected intercourse frequently during the fertile period. For approximately a week (several days before and after ovulation), couples are advised to have intercourse every other day. This ensures that there will be living, healthy sperm in the woman's body when the egg is ovulated and maximizes the chances of conception.
References
- "What to Expect When You're Expecting"; Heidi Murkoff and Sharon Mazel; 2008
- "Conception, Pregnancy and Birth"; Miriam Stoppard, M.D.; 2008
