Praise be to Allah.
Perhaps you are referring to the report that was narrated by at-Tabaraani in al-Mu‘jam al-Awsat (6733), and Ibn ‘Asaakir in his Tareekh (43/348), via ‘Amr ibn Sa‘eed al-Khawlaani from Anas ibn Maalik, according to which Salaamah the nurse of Ibraaheem, the son of the Prophet (blessings and peace of Allah be upon him), said: O Messenger of Allah, you give the men all kinds of glad tidings but you do not give the women such glad tidings? He said: “Would it not please one of you that if she is pregnant from her husband and he is pleased with her, that she will have the reward of one who fasts and prays qiyaam for the sake of Allah?...”
This hadeeth is fabricated. It was narrated by Ibn al-Jawzi in al-Mawdoo‘aat (2/274). He said:
Ibn Hibbaan said: ‘Amr ibn Sa‘eed is the one who narrated this fabricated hadeeth from Anas; it is not permissible to quote it except by way of highlighting an example of a fabricated hadeeth. And as-Suyooti agreed with him in al-La’aali’, 2/175
End quote. Silsilat al-Ahaadeeth ad-Da‘eefah wa’l-Mawdoo‘iyyah (5/76).
It was also narrated by Ibn Hibbaan in al-Majrooheen (1/238) and by Ibn ‘Adiyy in al-Kaamil (3/167) via al-Hasan ibn Muhammad al-Balkhi from ‘Awf al-A‘raabi from Ibn Sireen from Abu Hurayrah, who said: The Messenger of Allah (blessings and peace of Allah be upon him) said: “If a woman becomes pregnant, she will have the reward of one who fasts, prays qiyaam, is devout, fears Allah and strives in jihad for the sake of Allah, may He be glorified and exalted.”
Ibn ‘Adiyy said: It is munkar (odd). It was also narrated by Ibn al-Jawzi in al-Mawdoo‘aat (2/274). Al-Albaani said in ad-Da‘eefah (5085): It is mawdoo‘ (fabricated).
There is no need for this fabricated report, because we have the report that was narrated by Imam Ahmad (1664) from ‘Abd ar-Rahmaan ibn ‘Awf (may Allah be pleased with him) who said: The Messenger of Allah (blessings and peace of Allah be upon him) said: “If a woman offers her five (daily) prayers, fasts her month (Ramadan), guards her chastity and obeys her husband, it will be said to her: Enter Paradise by whichever of its gates you wish.”
Classed as saheeh by al-Albaani in Saheeh al-Jaami‘, 660
And Allah knows best.