Hadith - Bukhari, Narrated Anas bin Malik

The Prophet  said, "Allah has appointed an angel in the womb, and the angel says, 'O Lord! A drop of discharge (i.e. of semen), O Lord! a clot, O Lord! a piece of flesh.' And then, if Allah wishes to complete the child's creation, the angel will say. 'O Lord! A male or a female? O Lord! wretched or blessed (in religion)? What will his livelihood be? What will his age be?' The angel writes all this while the child is in the womb of its mother."

There are Angels entrusted with developments in the womb. One hadith tells us, "The Messenger of Allah, may Allah bless him and grant him peace, whose truthfulness is confirmed, said "The way that each of you is created is that you are gathered in you mother's womb for forty days as a sperm-drop and then for a similar length of time as a lump of flesh. Then an angel is sent and he breathes the spirit into you and is charged with four commands: to write down your provision, your life-span, you actions, and whether you will be wretched or happy." (Al-Bukhari and Muslim)

According to another, the Prophet (PBUH) said, "Allah has put an angel in charge of the womb. He says, "O Lord, a drop? O Lord, a clot? O Lord, a morsel?" When Allah desires to complete the creation of the fetus, he says, "O Lord, male or female? Wretched or happy? How much provision? How long a lifespan?" And he writes that for him in his mother's womb." (Al-Bukhari and Muslim)

Angels are creations of Allah, separate from human beings. According to Ibn Hajar, Sa'id bin al-Musayyab, "The angels are neither male nor female. They neither eat nor drink. They do not marry nor have children."