Jakarta, erection are not only experienced by men as adults, but since I was a child. Even while in the womb, the penis can men have erections even if it is not triggered by sexual stimuli.
Quoted from Birthpsychology, Friday (11/03/2011), erection of the earliest experienced male fetus when the gestational age entering the 4th month. Another source said the fetus had an erection when a man begins to feel a sense of pleasure which is marked with a thumb sucking habit.
It is not known exactly what causes an erection in the womb but the alleged fetus to feel the pleasure experienced by the mother. According to research, orgasms experienced by pregnant women can increase the heartbeat of the fetus up to 30 times / minute.
Meanwhile, when it was born, more frequent erections occur when the baby wanted to urinate. Bladder feel full can lead to tension and increase blood flow around the genitals male babies so they can get an erection.
Despite an erection, the penis fetus and a baby boy can not ejaculate until the age of puberty. Ejaculate or semen discharge occurs the first time at the age of about 13-14 years, either through wet dreams or masturbation.
One of the interesting facts about ejaculation is, only 13 percent of men who get it through wet dreams while the rest is through masturbation. This is because most of the first men known to masturbate before getting wet dream.
If the erection has occurred first in the womb, erection last experienced at different times in every man. For those with diabetes, the last erection can happen at the age of 30-40 years due to complications that lead to erectile dysfunction.
In contrast to the experience priapism, or erection unwanted, menegangnya genitals can also occur when a man already in a state of lifeless. Priapism can be triggered by a stimulant drug overdose, spinal cord injury or unnatural death such as hanging himself.
source: http://health.detik.com/read/2011/03/11/081000/1589231/763/pria-sudah-bisa-ereksi-sejak-dalam-kandungan-ibu?l991101755