Male baby pregnancies are more likely to result in complications, possibly because they grow faster in the womb and require more nutrients and oxygen than supplied by the mother through the placenta -- the temporary organ that attaches to the wall of the uterus during pregnancy to help the fetus grow and develop.
Specifically, it discovered that giving birth to girls may hurt less than giving birth to boys. The process of childbirth can generate a lot of stress in women and also in babies. According to a study conducted in Spain, there are differences in the intensity of pain when giving birth to girls versus boys.
“Male babies on average have greater difficulty self-regulating their emotional state and therefore have a greater reliance on emotional support, especially from their mother1,” he says. Research indicates that the slower development of baby boys' brains is likely due to the male hormone testosterone2.
Short of medically implanting an embryo that is known to be a boy, there are no guarantees when it comes to the sex of your baby. In general there is approximately a 50/50 chance of having a boy or girl if things are left to nature. It all comes down to which sperm wins the race, and millions of them are racing.
The key to conceiving a boy is to do “the deed” close to your ovulation. As Dr Shettles points out, male-producing sperm (Y-chromosome) move faster than female sperm. Male sperm also dies pretty fast, while female-producing sperm (X-chromosome) can stick it out and take their time hooking up with the egg.
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.
But that's not exactly true – there's actually a slight bias toward male births. The ratio of male to female births, called the sex ratio, is about 105 to 100, according to the World Health Organization (WHO). This means about 51% of deliveries result in a baby boy.
There are many ideas about ways to influence baby's sex and how to conceive a boy or a girl, but these are mostly myths or "old wives' tales" that aren't supported by modern science. The only reliable way to choose a baby's sex is by using IVF with genetic testing.
"Of the women carrying male infants, 70 per cent of them had completely normal deliveries, compared to 76 per cent of females." Baby-boy labour averaged more than six hours, while average baby-girl labour lasted less than six hours. Forceps were needed in 23 per cent of boy births, but only 19 per cent of girl births.
Research shows girls kick as often as boys. Babies who kick a lot in the womb are also more active after birth. Some mothers have more trouble feeling the kicks than others. If the placenta is on the front side of the womb, or if you are overweight, you will feel the kicks less.
Normal term newborn boys react differently to neonatal behavior assessment, showing higher cortisol levels (a mobilizing hormone indicating stress) afterward than girls. At six months, boys show more frustration than girls do. At 12 months, boys show a greater reaction to negative stimuli.
Worldwide, boys are heavier than girls at term birth. This difference is thought to be generated by androgen action [2], but its time course during fetal life is unknown.
Only 7.6 percent percent of male babies and 5.5 percent of female babies were in the womb 42 weeks or longer. Males were also 1.5 times more likely to be born at 43 weeks or longer. The researchers noted that the most common reason for prolonged pregnancies is an error in calculating the due date.
Boys are 14% more likely to be born prematurely than girls, according to new figures, which show an extra 5,700 boys are born early each year in the UK.
The Y chromosome, which makes boys, contains less DNA than the X chromosome for girls. That means sperm that bear a Y chromosome swim faster in viscous liquids.
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).
The mother gives an X chromosome to the child. The father may contribute an X or a Y. The chromosome from the father determines if the baby is born as male or female.
Another study that evaluated the relationship between age and semen parameters also concluded that male fertility decline begins at 35, and suggested that male fertility peaks between 30 and 35. Bottom line: Men generally see a decrease in fertility beginning at 35, and the decline progresses from there.
Physical size and growth
Right from the start, boys tend to weigh more at birth and this trend continues as babies age, with girls measuring about a half pound less. But girls catch right up as the toddler years approach. Most of them reach half their adult height by 19 months of age.
When mothers gained 20 lb, roughly 49% of babies born were boys. But when mothers gained 40 lb, the likelihood of having a boy increased, with about 52.5% of babies born being males. And at 60 lb gained, about 54% of babies were boys.
At birth, boys tend to be longer than girls at any placental weight. Boy's placentas may therefore be more efficient than girls, but may have less reserve capacity. In the womb boys grow faster than girls and are therefore at greater risk of becoming undernourished.
Girls undergo puberty earlier than boys by about 1-2 years, and generally finish the stages of puberty quicker than males due to their differences in biology.
Genetic factors and maternal conditions such as obesity or diabetes can cause fetal macrosomia. Rarely, a baby might have a medical condition that makes him or her grow faster and larger. Sometimes it's unknown what causes a baby to be larger than average.
Women, compared to men, have higher percent body fat and deposit it in a different pattern, with relatively more adipose tissue in the hips and thighs. This 'female' fat distribution, independent of total body fat, confers protection against metabolic diseases, such as type 2 diabetes and atherosclerosis [1].