Having difficulty getting pregnant can have many causes – some of them you cannot change, such as age, and some of them you can change.  If you want to get pregnant, the first step is working with your doctor to find out what your fertility issues are. 

Throughout history, failure to conceive was assumed to be a problem with the woman. We now know that's not the case as infertility problems are no more common in one sex than the other.  About 30-to-40 percent of infertility is diagnosed as a female problem, 30-to-40 percent as a male problem, 10-to-20 percent related to both and the remainder remains unknown. 

Couples are generally advised to seek medical help if they've been unable to conceive after having regular, unprotected intercourse for at least one year.  Women and men are usually advised to consult with a doctor sooner if:

Risk Factors for Infertility
Risk factors include:

• Age.  Women's fertility generally begins to decline much earlier than we think. Peak fertility occurs during the early 20s, begins to decline in the early 30s and accelerates after age 35.  Few unassisted pregnancies are recorded after the age of 45.  It's estimated that up to 1/3 of couples over 35 won't be able to have a successful pregnancy without assistance.  As women age the quality and quantity of eggs that remain in the ovary decrease while their chances of having health problems that may interfere with fertility increase.  A gradual decline in fertility is possible in men older than 35, too.  While the changes may not be as clearly defined as they are in women, age 50-and-over males often may find a decline in their quality of sperm, and sometimes discover a slight drop in testosterone levels and a dwindling libido.
  
  
• Weight extremes and poor nutrition. Being overweight or underweight can affect hormone production.  Infertility problems can be caused by a lack of important nutrients such as vitamin B-12, zinc, iron and folic acid.
  
  
• Alcohol, tobacco and street drugs. These substances may impair your ability to conceive or produce a healthy child. Miscarriages are more frequent in women who smoke.  Men who smoke may have a lower sperm count than do those who don't smoke.
  
  
• Prescription and over-the-counter medications.  Both prescription and nonprescription drugs can decrease your chance of getting pregnant or maintaining a pregnancy.
  
  
• Excessive exercise. Very intense exercise can cause menstrual irregularities and even amenorrhea (having no periods at all).
  
  
• Emotional stress. It's believed that stress may interfere with certain hormones needed to produce sperm and healthy eggs. 
  
  
• Environmental factors. Exposure to toxins and chemicals can reduce reproductive function by altering the hormonal system.

Diagnosing Infertility
Identifying a cause for a couple's infertility is key to recommending treatment. Both partners are involved in the process and the cause may be linked to either the man or woman or both.  

Common infertility problems in women include:

• Tubal disease and damage.  This accounts for approximately 1/3 of all causes of infertility in women.  Damage to the fallopian tubes can be caused by inflammation as a result of viral or bacterial infections, some types of sexually transmitted diseases, or complications of surgery.
  
  
• Ovulation disorders.  Hormone imbalances, the presence of cysts or tumors and ovarian failure can cause infertility in women. 
  
  
• Uterus and cervical disorders.  These include uterine fibroids or polyps, endometriosis, abnormalities in the shape of the cervix or changes in the properties of the cervical mucus.

Common infertility problems in men include:

• Low sperm volume.  A normal sperm concentration is greater than or equal to 20 million sperm per milliliter of semen. A count of less than 20 million sperm per milliliter of semen indicates low sperm concentration.  Low sperm volume may be caused by undescended testicles, testicular injuries and testosterone deficiency but, in many instances, no cause for reduced sperm production is found.
  
  
• Low sperm motility.  If movement (motility) is impaired, sperm may not be able to reach the egg.
  
  
• Abnormal sperm.  If the shape and structure of the sperm are abnormal, a sperm may not be able to penetrate an egg.
  
  
• Sperm antibodies.  Some men produce antibodies to their own sperm, which prevent the sperm from penetrating the egg.
  
  
• Blockage of sperm delivery ducts.  Blockages can be a result of a birth defect, vasectomy, infection and some sexually transmitted diseases.
  
  
• Retrograde ejaculation. This occurs when semen enters the bladder during orgasm rather than emerging out through the penis and may be caused by diabetes, bladder, prostate or urethral surgery, and the use of psychiatric or antihypertensive drugs.
  
  
• Varicocele. This is a varicose vein in the scrotum that may prevent normal cooling of the testicle and raise testicular temperature, preventing sperm from surviving.
  
  
• Previous vasectomy. Although surgery to reverse vasectomies is possible, risks are involved that could affect fertility in other ways.