Trying to Conceive  Myths and Truths

by Marjorie Greenfield, M.D.
reviewed by  Laura Jana M.D., F.A.A.P.

Chance plays a major role in determining when you get pregnant. On average, if the sperm arrive when the egg is ready for fertilization, only about 30 percent of women will miss their next menstrual period and have a positive pregnancy test. The remaining 70 percent, despite doing everything right, will have to wait and try again. When you're trying to become pregnant, these odds can seem just fine if you are in the 30 percent group and conceive within the first few months, but it can be very frustrating if your number doesn't come up.

Rumors abound as to when is the best time in a woman's cycle to conceive, how frequently a couple should have intercourse, which sexual practices and positions are most effective, and whether it decreases your odds of getting pregnant if you stand up immediately after intercourse. Here are the facts.

Best time to concieve
Ovulation occurs 14 days before the next period comes. For women with a 28-day cycle, this is about day 14; in women with a 35-day cycle, this would be around day 21; and in women with a 23-day cycle, this might be day 9. If you have a varied number of days between periods, you won't be able to accurately predict ovulation without using additional means, such as an ovulation detection kit.

Sperm can live in the woman's body for a few days, waiting for the egg, but the egg only lives about 24 hours once ovulation has occurred. Because of this, sex a few days before ovulation is more likely to produce a pregnancy than is sex a day or two later.

Frequency of intercourse
In couples with normal fertility, how often they have sex isn't important as long as the sperm are there in time to meet up with the egg. That said, maximal sperm counts are seen with ejaculation at 24- to 48-hour intervals, so "saving up" sperm for the big occasion probably won't help and may actually decrease your chances of conception. In general, couples should have sex at whatever interval feels right to them (which may be once a day or once every few weeks), with extra attention given to having sex at least every other day around ovulation time.

Sexual practices
There is no evidence that one position for intercourse is better than any other, as long as the penis is inside the vagina during ejaculation. Female orgasm probably has no significant role in conception--it neither helps nor hinders the sperm meeting up with the egg. Some lubricants used for sex can kill sperm, so if you are using a lubricant, make sure it's nontoxic. One other interesting issue: The testes hang outside the body because sperm number and motility are higher at cooler temperatures, so taking a hot bath before trying to conceive probably doesn't help a man's chances and may actually temporarily diminish his fertility.

Moving around afterward
Many women worry that because semen often runs back out of the vagina after sex, there won't be enough sperm left inside to fertilize the egg. Amazingly, sperm are already in the cervix moments after ejaculation. No evidence has been found to show that lying with legs or hips raised after sex improves fertility.

You'll probably want to avoid douching immediately after intercourse, however, since douches may be mildly toxic to sperm.