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Pregnancy is the period of time during which the fetus develops, dividing via mitosis inside the uterus. During this time, the fetus receives all of its nutrition and oxygenated blood from the mother, filtered through the placenta , which is attached to the fetus' abdomen via an umbilical cord .
Recent research displays that there is a correlation between fine motor skills and prenatal risk factors such as the use of psychoactive substances and signs of abortion during pregnancy. As well as perinatal risk factors such as gestation time, duration of delivery, birth weight and postnatal risk factors such as constant falls. [37]
Gestational age is the time that has passed since the onset of the last menstruation, which generally or as standard occurs 2 weeks before the actual fertilization. Embryonic age, in contrast measures the actual age of the embryo or fetus from the time of fertilization. Nevertheless, menstruation has historically been the only means of ...
Mammals during pregnancy can have one or more gestations at the same time, for example in a multiple birth. [2] The time interval of a gestation is called the gestation period. In obstetrics, gestational age refers to the time since the onset of the last menses, which on average is fertilization age plus two weeks. [3]
Smoking during pregnancy may also lead to miscarriages and low birth weight (2,500 grams (5 pounds 8 ounces). Low birth weight is a concern for medical providers due to the tendency of these infants, described as " premature by weight", to have a higher risk of secondary medical problems.
Preterm birth is the birth of an infant at fewer than 37 weeks gestational age. Globally, about 15 million infants were born before 37 weeks of gestation. [147] Premature birth is the leading cause of death in children under five years of age though many that survive experience disabilities including learning defects and visual and hearing ...
Nine-week-old human embryo from an ectopic pregnancy. Organogenesis is the development of the organs that begins during the third to eighth week, and continues until birth. Sometimes full development, as in the lungs, continues after birth. Different organs take part in the development of the many organ systems of the body.
The average time to birth has been estimated to be 268 days (38 weeks and two days) from ovulation, with a standard deviation of 10 days or coefficient of variation of 3.7%. [33] Fertilization age is sometimes used postnatally (after birth) as well to estimate various risk factors.