Posted: March 23rd, 2009 | Author: Editor | Filed under: parenting, pregnancy, women's health | Tags: birth, childbirth, delivery, fraternal twins, health, identical twins, labor, motherhood, new mom, parenting, pregnancy, twinning, twins | No Comments »
Statistics vary but about one in every ninety births in the United States are twins, and sometimes the propensity to have twins can run in families. There are two main types of twins, identical and fraternal. Identical twins occur when a single fertilized egg splits in two, usually before the eighth day of development. Each then develops into two separate but genetically identical embryos. Heredity and family history seem to play no role in the occurrence of identical twins.
There does seem to be a genetic link to some fraternal twins. Fraternal twins usually result when two eggs are released from the ovaries, and each egg is fertilized by a different sperm cells. This results in two separate and genetically distinct embryos. Since specific genes can cause a woman to hyper-ovulate, and release more than a single egg during each menstrual cycle, the tendency to have fraternal twins can be passed along in families carrying those genes. But still, most twins will not give birth to twins.
Nutrition may also increase the odds of having fraternal twins. The highest rates of fraternal twinning in the world are found in certain parts of West Africa where a lot of cassava is eaten. The peel of this potato-like root is thought to contain a substance that causes women to hyper-ovulate.
-Sean Kenniff, MD
Posted: March 18th, 2009 | Author: Editor | Filed under: Sex, pregnancy, women's health | Tags: Add new tag, menstrual bleeding, menstruation, pregnancy, Sex, women, women's health | No Comments »
For many women, having sexual intercourse during menstrual bleeding carries a lower risk of conception than having sex during mid-cycle. But it is still quite possible to become pregnant during menstruation for several reasons.
Most women ovulate during mid-cycle, around days 12-16 of a 28-day cycle. But some women, especially teenagers and young adults, have irregular ovulation. The egg for the following cycle can be released from the ovary during menstrual bleeding or a few days afterward. Since sperm can survive for five days or longer in the uterus that egg can be fertilized.
Women with shorter menstrual cycles (21 days) and longer periods (7-days) may be most at risk for conceiving during her period. Women often mistake other causes of vaginal bleeding with menstrual bleeding and sexual activity results in pregnancy. In fact it’s normal for some women to ‘spot’ or bleed a little during ovulation-the most fertile time of the cycle.
The best way to prevent pregnancy is of course through abstinence and the judicious use of contraceptive devices and drugs. Birth control pills are very effective, but condoms have an added benefit. Some studies have show the risk of transmitting and contracting a sexually transmitted disease is increased during menstrual bleeding. -Sean Kenniff, MD
