Even small children are aware that men and women usually look different. It is common knowledge that boys become men because the testes of the man produce the “male” hormone testosterone and, in turn, testosterone makes men masculine.
High concentrations of testosterone and oestrogen increase the chances of having a son, and high concentrations of progesterone and luteinising hormone favour girls. The general rule is: more testosterone in women, and it's boys, less testosterone in men and it's girls.
Hormone differences for baby boys and girls
Studies have shown hCG (human chorionic gonadotropin, the hormone responsible for the second line appearing on a home pregnancy test) is higher for female fetuses compared with males, and remains higher throughout pregnancy. Some studies only report this later in pregnancy.
Circulating levels of the placental glycoprotein hormone human chorionic gonadotropin (hCG) are higher in women carrying female v. male fetuses; yet, the significance of this difference with respect to maternal factors, environmental exposures and neonatal outcomes is unknown.
In mammals, high parental testosterone levels present around the time of conception are thought to skew offspring sex ratio toward sons.
In regard to gender identity, or one's sense of self as male or female, exposure to high levels of androgens prenatally has been linked to an increased likelihood of developing a male gender identity, despite being reared as a female [32].
Testosterone is a major influence on bodily and behavioral features seen as male and/or masculine.
The hCG levels in female-bearing pregnancies increase significantly, whereas they decrease in male-bearing pregnancies [1–3].
It appeared that in women carrying a male fetus testosterone levels gradually increased during pregnancy up to 3.99 +/- 2.72 nM/l. In women carrying a female fetus the levels decreased after the first trimester from 2.44 nM/l to 1.80 nM/l.
Progesterone (P4) is an endogenous hormone with an important role for the physiology of the reproductive system of cisgender females.
Here's the science: Eggs carry the female X sex chromosome, while sperm carry either the female X or male Y chromosome. If the egg is fertilized with the X chromosome sperm, you will conceive a girl. If the egg is fertilized with the Y chromosome sperm, you will conceive a boy.
Men determine the sex of a baby depending on whether their sperm is carrying an X or Y chromosome. An X chromosome combines with the mother's X chromosome to make a baby girl (XX) and a Y chromosome will combine with the mother's to make a boy (XY).
Nature is designed to favour the conception of boys from September to November and girls from March to May because of an evolutionary mechanism aimed at keeping the overall sex ratio as near to 50:50 as possible, the scientists said.
A baby's biological sex is determined by the two sex chromosomes in the egg and sperm. Eggs always have an X chromosome, and sperm have either an X or a Y chromosome. Whichever sperm is the winner will penetrate and fertilize the egg, creating either an XX (girl) or XY (boy) pair.
A recent study suggests that carrying a male or female foetus could lead to different immune responses in pregnant women. Pregnant women carrying girls have a greater chance of experiencing nausea and fatigue, according to the results of a study from the USA's Ohio State University Wexner Medical Center.
Since a baby's gender also shows up in a pregnant mother's blood, expectant parents now have the option of a pregnancy gender blood test as a non-intrusive alternative. It provides the exciting answer to your baby's gender as early as 9 weeks into pregnancy.
Human chorionic gonadotropin (hCG).
This is a hormone released by some cells in the placenta. High hCG levels may mean that the baby has Down syndrome. This condition is a chromosome problem. It causes learning problems and some physical changes.
Levels of the pregnancy hormone hCG, which triggers morning sickness, tend to be higher in mothers who are pregnant with girls. But anyone who's pregnant can have morning sickness, even bad morning sickness, when they're carrying a boy.
Scientists have found that boys whose fathers play no role as they go through adolescence tend to have higher testosterone levels when they become men. High testosterone has been linked to aggressiveness, with some studies finding that 'macho' men tend to make worse fathers.
If your body produces too much testosterone, you may have irregular or absent menstrual periods. You may also have more body hair than the average woman. Some women with high testosterone levels develop frontal balding.
Feminizing hormone therapy involves taking medicine to block the action of the hormone testosterone. It also includes taking the hormone estrogen. Estrogen lowers the amount of testosterone the body makes. It also triggers the development of feminine secondary sex characteristics.