for women are not always lived in good health." Health Factors that specifically affect the health of women vs. men are most evident in those related to reproduction, but sex differences have been identified from the molecular to the behavioral scale. Some of these differences are subtle and difficult to explain, partly due to the fact that it is difficult to separate the health effects of inherent biological factors from the effects of the surrounding environment they exist in. Sex chromosomes and hormones, as well as sex-specific lifestyles, metabolism, immune system function, and sensitivity to environmental factors are believed to contribute to sex differences in health at the levels of physiology, perception, and cognition. Women can have distinct responses to drugs and thresholds for diagnostic parameters. Some diseases primarily affect or are exclusively found in women, such as lupus, breast cancer, cervical cancer, or ovarian cancer. The medical practice dealing with female reproduction and reproductive organs is called gynaecology ("science of women"). Maternal mortality Maternal mortality or maternal death is defined by WHO as "the death of a woman while pregnant or within 42 days of termination of pregnancy, irrespective of the duration and site of the pregnancy, from any cause related to or aggravated by the pregnancy or its management but not from accidental or incidental causes." In 2008, noting that each year more than 500,000 women die of complications of pregnancy and childbirth and at least seven million experience serious health problems while 50 million more have adverse health consequences after childbirth, the World Health Organization urged midwife training to strengthen maternal and newborn health services. To support the upgrading of midwifery skills the WHO established a midwife training program, Action for Safe Motherhood. In 2017, 94% of maternal deaths occur in low and lower middle-income countries. Approximately 86% of maternal deaths occur in sub-Saharan Africa and South Asia, with sub-Saharan Africa accounting for around 66% and Southern Asia accounting for around 20%. The main causes of maternal mortality include pre-eclampsia and eclampsia, unsafe abortion, pregnancy complications from malaria and HIV/AIDS, and severe bleeding and infections following childbirth. Most European countries, Australia, Japan, and Singapore are very safe in regard to childbirth. In 1990, the US ranked 12th of the 14 developed countries that were analyzed and since that time the death rates of every country have steadily improved while the US rate has spiked dramatically. While the