Electrical brain activity is first detected at the end of week 5 of gestation, but as in brain-dead patients, it is primitive neural activity rather than the beginning of conscious brain activity. Synapses do not begin to form until week 17. Neural connections between the sensory cortex and thalamus develop as early as 24 weeks gestational age, but the first evidence of their function does not occur until around 30 weeks, when minimal consciousness, dreaming, and the ability to feel pain emerges.Although the fetus begins to move during the first trimester, it is not until the second trimester that movement, known as quickening, can be felt. This typically happens in the fourth month, more specifically in the 20th to 21st week, or by the 19th week if the woman has been pregnant before. It is common for some women not to feel the fetus move until much later. During the second trimester, when the body size changes, maternity clothes may be worn. Maternal changes
During pregnancy, a woman undergoes many physiological changes, which are entirely normal, including behavioral, cardiovascular, hematologic, metabolic, renal, and respiratory changes. Increases in blood sugar, breathing, and cardiac output are all required. Levels of progesterone and estrogens rise continually throughout pregnancy, suppressing the hypothalamic axis and therefore also the menstrual cycle. A full-term pregnancy at an early age (< 25) reduces the risk of breast, ovarian and endometrial cancer and the risk declines further with each additional full-term pregnancy.
In the US, the average age of first childbirth was 25.4 in 2010.In the United States and United Kingdom, 40% of pregnancies are unplanned, and between a quarter and half of those unplanned pregnancies were unwanted pregnancies.In the US, a womans educational attainment and her marital status are correlated with childbearing: the percentage of women unmarried at the time of first birth drops with increasing educational level. In other words: among uneducated women, a large fraction (~80%) have their first child while they are unmarried. By contrast, few women with a bachelors degree or higher (~25%) have their first child while unmarried. However, this phenomenon also has a strong generational component: in 1996, about 50% of women without a university degree had their first child being unmarried while that number increased to ~85% in 2018. Similarly, in 1996, only 4% of women with a BA degree or similar had their first child being unmarried. In 2018, that fraction increased to ~25%. Legal and social aspects
Legal protection
Many countries have various legal regulations in place to protect pregnant women and their children. Many countries have laws against pregnancy discrimination.Maternity Protection Convention ensures that pregnant women are exempt from activities such as night shifts or carrying heavy stocks. Maternity leave typically provides paid leave from work during roughly the last trimester of pregnancy and for some time after birth. Notable extreme cases include Norway (8 months with full pay) and the United States (no paid leave at all except in some states).