Hadith 31-272

وَبِإِسْنادِهِ عَنْ عَلِيِ‏ عَلَيْهِ السَّلامُ قالَ: نَهَى النَّبِيُ‏ صَلَّى اللهُ عَلَيْهِ وَآلِهِ: عَنْ وَطيِ الحُبالى‏ حَتّى‏ يَضَعنَ.

According to the same documentation, it is narrated that Ali (a.s.) said, “The Prophet (S) admonished men against making love with pregnant women until they deliver.”