SPONTANEOUS CONCEPTION AND FERTILITY

1. Ovulation
   
   
   
   
   Fourteen days prior to the beginning of a new cycle, an ovarian follicle releases a microscopic egg.
   
   
2. Fertilization
   
   
   
   
   Sperm, which can wait in the Fallopian tubes for several days, must fertilize the egg within 12 to 16 hours of ovulation.
   
   
3. Early Embryonic Development
   
   
   
   
   The fertilized egg moves through the Fallopian tube and starts to divide the day after fertilization. In two days, it has 4 cells. In three days, 8 cells and in six days it has over 100 cells.
   
   
4. Implantation
   
   
   
   
   This embryo then hatches out and implants into the lining of the uterus and starts to produce the pregnancy hormone (hCG).
   
   
5. Endometrial Lining
   
   
   
   
   Female hormones estrogen and progesterone, produced by the ovulating follicle, have prepared the lining of the uterus for implantation.

Infertility is classically defined as 12 months of unprotected intercourse without achieving a pregnancy. This definition does not take into account the importance of the individual. It is clearly a different situation if the couple is in their early twenties as opposed to their early forties.

Speed of conception in the general population
	Once a couple has been sexually active without contraception for a year, it is unlikely that they will achieve a spontaneous pregnancy. There is only a 1.5% probability of a conception during the next ovulation. After 2 years, the probability is only 1 in a 1000.

There is no distinction between not using contraception and "trying" to conceive. Women older than 35 years should seek an infertility specialist after 6 months of sexual activity without contraception; 3 months after the age of 40.

The causes of infertility fall into three main areas:

• Male Factor: Sperm production and sperm quality.
  
  
• Ovulation: Egg production, egg quality and preparation of the uterine lining for implantation.
  
  
• Passage: The joining of sperm and egg in the Fallopian tubes and transport of the fertilized egg into the uterus.

Female Age and Fertility
	The loss of female fertility is due to the loss of high quality eggs. The receptiveness of the uterus is not decreased. This loss of fertility magnifies the impact of any other fertility factors present.

Please see Female Fertility Potential for additional information about the impact of female aging.

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