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Becoming Pregnant

There are several important steps that must occur with relative precision to achieve pregnancy.

Step 1: Ovulation and Sperm Production – First, the woman must release an egg near the middle of her menstrual cycle, a process termed ovulation. In addition, the man must produce an adequate number of functional sperm.

Step 2: Transport – Immediately after ovulation, the tube must pick up the egg and transport it to the portion of the tube where fertilization occurs.

Step 3: Fertilization – Within 24 hours of ovulation, a couple must have intercourse and an adequate number of motile sperm must make their way through the cervical mucus and uterus to the distal end of the tube to fertilize the egg. If a women is using insemination, the insemination should occur within 1 day of ovulation.

Step 4: Implantation – During the first 5 to 6 days after fertilization, the embryo must be transported by the tube into the uterus and must implant into the uterine lining.

Step 5: Support – For at least 5 weeks after implantation, the growing pregnancy must be supported by hormones from the ovary (estrogen and progesterone) until the placenta can take over production of these hormones.

If just one of these steps does not occur, another month will pass without achieving pregnancy. In light of the complexity of the process, it is not surprising that few couples achieve pregnancy on the first try or that many couples without any history of reproductive problems experience some difficulty.

It Can Take Months to Achieve Pregnancy

Most couples are surprised to discover that it often takes several months of active “trying” to achieve pregnancy. Keep in mind that:

  • Many healthy couples will have to try for 3 to 6 months to achieve success.
  • For those with normal fertility, the chance of getting pregnant each month is 20%. 
  • Approximately 80% of couples will achieve pregnancy within a year of trying.

For these reasons, it is recommend that women less than 35 years old try for up to a year to achieve pregnancy, and women 35 or older try for 6 months on their own before seeking medical assistance.

This is assuming that a woman has regular monthly menstrual periods and that there are no known fertility problems. If there is a known issue, help should be sought earlier. Several good guides are available to improve the chances of becoming pregnant by increasing your understanding of the factors that affect fertility.


  • American Society for Reproductive Medicine. Infertility: an overview, United States. 2003. Birmingham, Ala: American Society for Reproductive Medicine.
  • Centers for Disease Control and Prevention. 2006 Assisted Reproductive Technology Success Rates, National Summary and Fertility Clinic Report. Atlanta: 2008.
  • Falcone T, Hurd WW, eds. Clinical Reproductive Medicine and Surgery, New York: Elsevier, 2007.

Prepared in partnership with Melina Dendrinos, MD, Class of 2008


To Learn More

For more information:

Go to the Infertility health topic.