Severe stress, maybe. Day-to-day stress, probably not. If just average stress levels could keep women from getting pregnant, nobody would ever get pregnant in a war zone or a bad relationship, and it happens all the time.
It sure can!
Stress in women disrupts the hormonal communication between the brain, the pituitary, and the ovary, interfering with both the maturation of an egg and the ovulation process.
When we are under stress, we experience several neurochemical changes. This can alter the ordered release of hormones that regulate the maturation and release of an egg. IN addition to this, the concentrations of several important chemical messengers involved in reproduction change when our emotional states change. There is a direct link between the brain and the reproductive tract. Nerve fibers connect the brain directly to both the fallopian tubes and the uterus. The autonomic nervous system influence the ovary's ability to produce healthy eggs and hormones. For example, when a woman is under stress, spasms occur in both the fallopian tubes and the uterus, which can interfere with movement and implantation of a fertilized egg.
Thus the stress can affect infertility both by the altered regulation of pituitary hormones and from the abnormal nervous-system influences on the ovaries and fallopian tubes.
In case of man, both physical and emotional stress are known to affect the fertility. Sperm counts, motility, and structure are altered under stress. Problems such as impotence and difficulties with ejaculation are often caused by the emotional distress in men.