Planning for pregnancy
The right time: when sperm and egg meet
You are so ready to have a baby, that it makes you crazy, and
besides, getting pregnant should be easy, right? So how do you make
it happen? Well, of course, we know you know how, but when it comes
to getting that sperm and egg together, believe it or not, it can get
a little tricky.
In a typical 28 day menstrual cycle, ovulation usually occurs around
ay 14—with Day 1 as the first day of your menstrual bleeding,
says Fady I. Sharara, MD, medical director of the Virginia Center for
Reproductive Medicine and associate clinical professor at George Washington
University School of Medicine. While the egg "fertilization window" is
short he says (just 12 to 24 hours), sperm can live up to five days—and
sometimes longer—in the cervical mucus, which is most
abundant close to ovulation.
"Every woman who is attempting to conceive should know whether
her cycles are regular and whether she experiences the 'ovulation
signs,'"he says. "These signs include increasing cervical mucus
close to ovulation, and what is called Mittleschmerz, or
the midcycle cramping that some, but not all, women feel."
While everyone is different, Randy S. Morris MD, a board-certified
reproductive endocrinologist and associate clinical professor at the
University of Illinois at Chicago, says most women have menstrual cycle
lengths between 26 to 30 days. "Ovulation in these women is usually
occurring between Day 12 and Day 16," he explains. "The first part of
the cycle from menstruation until ovulation is called the follicular
phase. The second part from ovulation until the next menstruation is
called the luteal phase. The luteal phase is relatively constant
at around 14 days."
Dr. Morris cites a study published in 1995 in the New England
Journal of Medicine which looked at the timing of intercourse
relative to ovulation. He says the following conclusions could be
made from this study:
- Pregnancy can be achieved when intercourse occurs up to five
days prior to ovulation. At three to five days before ovulation, the
probability of conception averaged around 10 percent.
- The highest chance for pregnancy occurs when intercourse happens
two days before, one day before or on the day of ovulation. On those
days, the probability of pregnancy averaged about 35 percent.
Statistically, there is no better chance for conceiving on any of
those three days.
- The probability for pregnancy drops off significantly (maybe to
zero) the day after ovulation.
- The frequency of intercourse made little difference in the
probability of conception.
For couples actively trying to conceive, Dr. Morris suggests the
First, figure out the length of your cycles from the first day
menstruation begins until the next first day of bleeding —
for example, 26 or 29 days.
Next, subtract 14 days for a good estimate of when you usually
ovulate. (e.g., 26-14=12 and 29-14=15. Ovulation in this example would
be expected between day 12 and 15 of any given cycle).
Then, have intercourse every two to three days leading up to
ovulation (In this example, intercourse on days 10, 12 and 14 would
maximize the chance for conception. Couples who want to have
intercourse more often such as every day, may do so without
compromising their chances for success, he says. Some doctors suggest
couples have sex every other day.
There are a number of ways to see if you are ovulating, from
keeping track of the changes in your cervical fluid, to charting
changes in your basal body temperature. There are also ovulation
predictor kits (OPKs) on the market today that test for signs of
ovulation by looking for hormonal changes in urine and even changes
in the salt of the saliva brought on by hormonal changes.
William B. Hummel, MD, co-founder of the San Diego Fertility Center
in San Diego, California, says if you have an irregular cycle, urine
OPKs that test for a hormone surge of luteinizing hormone (LH) help
women identify their most fertile time. "Generally, the most fertile
time of a woman's cycle is the day after the LH surge. This fertile
period of time may be associated by an increase in one's basal body
temperature the day after ovulation," he says.
Dr. Sharara says many women chart their basal body temperature
(BBT), which is done by taking your temperature as soon as you wake
up—before getting out of bed or doing anything—and
recording it on a special chart. "Impending ovulation is often
associated with a drop in the temperature from the baseline, followed
by an increase the next day," he says.
Temperature charting does not predict ovulation, says Dr. Morris,
but it can detect ovulation only after it has already occurred. "There
is no reliability in predicting ovulation. It is useful for women with
irregular or infrequent menstrual cycles to determine if they are
ovulating," he says.
Today, says Dr Sharara, the most "scientific" approach involves
using a urine-based OPK. "When the kit turns 'positive' that implies
that ovulation will occur within 24 hours," Dr. Sharara notes. "Therefore
intercourse has to be timed as close to ovulation as possible to
achieve the highest chances at conception."
Lawrence Werlin, MD, FACOG, reproductive endocrinologist and
founder and director of the Coastal Fertility Medical Center in
Irvine, California, says women need to understand what changes occur
in their own cycles and to understand what those changes mean. "For
example, when her (cervical) mucus begins to change, and become thin
(watery), clear and sticky, she is close to ovulation," says Dr. Werlin.
Dr. Sharara says it is also important your partner be tested, to
ensure he doesn't have a low sperm count. "Male-related infertility
accounts for 40 percent of all infertility
causes, and in an additional 20 percent, both partners have fertility
problems," he says.
About the Author:
Jennifer Newton Reents is a freelance journalist and publicist. She earned a bachelor's degree in journalism in 1994 from San Diego State University and worked for several newspapers as reporter, covering various beats, from the courtroom and crime to education and business, before moving to a freelance career in 2000. She is the former associate editor of Pregnancy and ePregnancy magazines and continues to contribute to various national magazines today. Her bylines have appeared in LowCarb Energy, Cooking Smart, And Baby, Southern Cooking and Lifestyles as well as numerous regional, local and web publications. She lives with her family in Texas.