Answered by: aulana Sibghat Ullah
Question:
Asalamu laikum. If a woman is pregnant is it ok to get a gender scan done
In the name of Allah, the Most Gracious, the Most Merciful
Answer:
There is nothing wrong with using fetal ultrasound to know the sex of your fetus since it does not change or alter the will of Allah
This question arises because some people think that only one has the knowledge of what is in the womb of the mother. They quote the ayat of the Quran in which Allah 
says
“Verily, Allah! With Him is the knowledge of the Hour, He sends down the rain, and knows that which is in the wombs. No person knows what he will earn tomorrow, and no person knows in what land he will die. Verily, Allah is All-Knower, All-Aware.”
The term “That which is in the wombs” here does not apply to the sex of the foetus, even though the sex may be at some earlier stage of the knowledge. It refers to everything about this creature and its future.
The proof of this is in the hadith of the Prophet 
in which he said,
“After the nutfah [drop (of semen)] is in the womb for forty or forty-five nights, the angel enters and says: My Lord, will he be good or evil? Both will be written. Then he says, My Lord, would he be male or female? Both will be written. In addition, his deeds, actions, death and livelihood will be recorded. Then his document of destiny is rolled and there shall be no addition to it or subtraction from it.” ii
Based on this, the earlier scholars did not reprimand physicians who attempted, through their rather primitive means, to guess the sex of a foetus.
Given the above, there is no harm in trying to know the sex of the baby before its birth through foetal ultrasound.
Only Allah knows best.
Written by Maulana Sibghat Ullah
Checked and approved by Mufti Mohammed Tosir Miah
Darul Ifta Birmingham
i Al Quran, Surah Luqman, 31 verse 34
ii Sahih Muslim, The Book of Destiny, Chapter: How The Human Being Is Created, In His Mother’s Womb, And His Provision, Lifespan And Deeds Are Written Down, And His Misery and Happiness