Causes in a male include low sperm count, a malfunctioning immune system, a varicose vein in the scrotum, heat exposure, structural sperm defects, and abnormal hormone levels. Infertility in a female can be due to absent or irregular ovulation, blocked fallopian tubes, an inhospitable uterus, or antisperm secretions. Assisted reproductive technologies include artificial insemination, surrogate mothers, IVF, GIFT, ZIFT, and embryo transfer. Preimplantation genetic diagnosis screens IVF preembryos for disease-causing genes. Spontaneous abortion is common and usually occurs because an embryo or fetus has an extra or missing chromosome or is due to a hormonal or structural abnormality in the woman's reproductive tract.
Babies born prematurely often experience several health problems.
Maternal infection may cause premature delivery. The nature of the defect reflects which structures were in critical periods when the insult occurred. Neonatology deals with the medical problems of newborns and includes fetal treatments. Contraceptives block the meeting of sperm and oocyte or make the uterus inhospitable to implantation of a zygote. Vasectomy and tubal ligation are permanent methods.