There are some fertility experts who claim that the high consumption of yams explains the higher than expected rate of twins pregnancies in the Igbo-Ora population in Nigeria.  It is well known that yams contain phytoestrogens, which can be converted to human estrogens.  If fact, the first source to make estrogens used in birth control pills was extracted from the yam.  It is also interesting that if you give a woman additional estrogen in the early part of her menstrual cycle you can actually suppress ovulation making her infertile.  Also in those populations that consume large amounts of soy beans (also containing phytoestrogens) there is no reported increase in twins in the population.

Most twin pregnancies result from the release of two eggs in the same menstrual cycle.  If both eggs fertilized and implanted there would be a higher than expected number of twin pregnancies.  I would be more likely that higher levels of FSH (follicle stimulation hormone) are released which would lead to the maturation and ovulation of two eggs simultaneously.  Such an effect is seen when taking the drug Clomid, which has an increase rate of twin pregnancies of 6 to 8%.  So it would seem that a diet containing a high consumption of yams would unlikely be the explanation of the increase of twin pregnancies in the Igbo-Ora population.  The more likely explanation would be a genetic predisposition toward twins which somehow gave this population a selective advantage to survive in their environment.

Tags: Becomming Pregnant, Conception, infertility, pregnancy