Short answer
It depends on what it involves. Many Hanafi scholars advise against baby showers and gender reveal parties as customs taken from non-Muslim culture that often bring waste and mixing. Others allow a simple gathering with dua and gifts. Knowing the baby's sex is not wrong.
Mainstream Hanafi fatwas discourage baby showers and gender reveal parties, and do not allow them where they involve imitation of non-Muslim rites, waste, free mixing or music. Giving gifts to an expecting mother is permissible, and the sunnah celebration of a birth is the aqiqah.
The four schools agree on this.
Explanation
This is a modern question that the four schools did not address by name. They share the principles below, and the difference is between contemporary scholars applying them.
The concerns raised:
- Imitation: the Prophet ﷺ warned that whoever imitates a people is counted among them. Many Hanafi muftis see these parties as a custom with no roots in Muslim life.
- Waste: expensive decorations, smoke cannons and showy reveals can become the extravagance the Quran criticises.
- Mixing and music: mixed parties or haram music make the gathering itself wrong.
The view that allows it: some scholars say that a party is a matter of custom ('urf), and a simple women's gathering where friends bring gifts, eat together and make dua for the mother and baby is permissible, as long as it avoids the problems above and is not treated as a religious rite. Both views are held by respected scholars.
On gender reveals: knowing the baby's sex by ultrasound does not contradict the ayah that Allah knows what is in the wombs. Allah's knowledge is complete, from before conception, while a scan only sees what is already formed. What matters more is the reaction: the Quran condemns those whose faces darken at the news of a girl. A daughter is a gift.
The sunnah way to celebrate is after the birth: the adhan, tahnik and the aqiqah meal shared with family and the poor.
The evidence
Quran, Surah Al-Furqaan 25:67
وَٱلَّذِينَ إِذَآ أَنفَقُوا۟ لَمْ يُسْرِفُوا۟ وَلَمْ يَقْتُرُوا۟ وَكَانَ بَيْنَ ذَٰلِكَ قَوَامًۭا ﴿٦٧﴾
And [they are] those who, when they spend, do so not excessively or sparingly but are ever, between that, [justly] moderate
Spending on celebrations should be moderate.
Quran, Surah Luqman 31:34
إِنَّ ٱللَّهَ عِندَهُۥ عِلْمُ ٱلسَّاعَةِ وَيُنَزِّلُ ٱلْغَيْثَ وَيَعْلَمُ مَا فِى ٱلْأَرْحَامِ ۖ وَمَا تَدْرِى نَفْسٌۭ مَّاذَا تَكْسِبُ غَدًۭا ۖ وَمَا تَدْرِى نَفْسٌۢ بِأَىِّ أَرْضٍۢ تَمُوتُ ۚ إِنَّ ٱللَّهَ عَلِيمٌ خَبِيرٌۢ ﴿٣٤﴾
Indeed, Allah [alone] has knowledge of the Hour and sends down the rain and knows what is in the wombs. And no soul perceives what it will earn tomorrow, and no soul perceives in what land it will die. Indeed, Allah is Knowing and Acquainted.
Allah's knowledge of the womb is complete and is not contradicted by a scan.
Quran, Surah An-Nahl 16:58
وَإِذَا بُشِّرَ أَحَدُهُم بِٱلْأُنثَىٰ ظَلَّ وَجْهُهُۥ مُسْوَدًّۭا وَهُوَ كَظِيمٌۭ ﴿٥٨﴾
And when one of them is informed of [the birth of] a female, his face becomes dark, and he suppresses grief.
Disappointment at having a girl is condemned.
Sunan Abi Dawud 4031
Graded hasan sahih... من تشبه بقوم فهو منهم ...
"Whoever imitates a people is one of them."
The basis of the concern about adopting other cultures' rites.
Where the ruling is recorded
- Fatawa Mahmudiyya, Chapter on customs and innovations. Hanafi fatwas on adopting customs of other communities in celebrations.
- Radd al-Muhtar (Ibn Abidin), Kitab al-Hazr wal-Ibaha, discussion of imitation. Imitation is blameworthy when it is in what is specific to another community.
This answer is pending review by the scholars on our team. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.