Lactulose is a non-absorbable sugar used in the treatment of constipation and hepatic encephalopathy. It is used by mouth for constipation and either by mouth or in the rectum for hepatic encephalopathy. It generally begins working after 8–12 hours, but may take up to 2 days to improve constipation.Common side effects include abdominal bloating and cramps. A potential exists for electrolyte problems as a result of the diarrhea it produces. No evidence of harm to the baby has been found when used during pregnancy. It is generally regarded as safe during breastfeeding. It is classified as an osmotic laxative.Lactulose was first made in 1929, and has been used medically since the 1950s. It is on the World Health Organizations List of Essential Medicines. It is available as a generic and brand-name product. Lactulose is made from the milk sugar lactose, which is composed of two simple sugars, galactose and glucose. History
In 1957, Peitele discovered that lactulose is a bifidobacterium proliferation factor. In 1964, Hoffman found that only bifidobacteria, Lactobacillus and Streptococcus could metabolise lactulose into lactic acid and acetic acid. In 1966, Baicier found that lactulose can promote the growth of basophilic gram-positive bacteria lacking urease (e.g. Escherichia coli) and reduce ammonia production. It has been proven that lactulose reduces blood ammonia, and it has been successfully used in the treatment of hepatic encephalopathy. In 1979, Nianmoleyou treated viral hepatitis with lactulose and he found that lactulose has the effect of reducing plasma endotoxin.
After total body irradiation, recovery of gonadal function occurs in 10−14% of cases, and the number of pregnancies observed after hematopoietic stem cell transplantation involving such as procedure is lower than 2%. Genetic factors
There are many genes wherein mutation causes female infertility, as shown in table below. Also, there are additional conditions involving female infertility which are believed to be genetic but where no single gene has been found to be responsible, notably Mayer-Rokitansky-Küstner-Hauser Syndrome (MRKH). Finally, an unknown number of genetic mutations cause a state of subfertility, which in addition to other factors such as environmental ones may manifest as frank infertility. Chromosomal abnormalities causing female infertility include Turner syndrome. Oocyte donation is an alternative for patients with Turner syndrome.Some of these gene or chromosome abnormalities cause intersex conditions, such as androgen insensitivity syndrome. By location
Hypothalamic-pituitary factors
Hypothalamic dysfunction
Hyperprolactinemia

Ovarian factors
Chemotherapy (as detailed previously) with certain agents have a high risk of toxicity on the ovaries. Many genetic defects (as also detailed previously) also disturb ovarian function. Polycystic ovary syndrome (also see infertility in polycystic ovary syndrome)
Anovulation. Female infertility caused by anovulation is called "anovulatory infertility", as opposed to "ovulatory infertility" in which ovulation is present. Diminished ovarian reserve, also see Poor Ovarian Reserve
Premature menopause
Menopause
Luteal dysfunction
Gonadal dysgenesis (Turner syndrome)

Tubal (ectopic)/peritoneal factors
Endometriosis (also see endometriosis and infertility)
Pelvic adhesions
Pelvic inflammatory disease (PID, usually due to chlamydia)
Tubal dysfunction
Previous ectopic pregnancy.