Praise be to Allah.
Shaykh Ibn Baaz (may Allaah have mercy on him) was asked whether a woman may be divorced by talaaq when she is pregnant. He said:
This is an idea which is common among some people. Some of the people think that a pregnant woman cannot be divorced by talaaq. I do not know where they get this idea from, for it has no basis in the words of the scholars. Rather the view of all the scholars is that a pregnant woman can be divorced by talaaq. There is consensus on this point among the scholars, and there is no dispute. Talaaq according to the Sunnah means that a woman may be divorced in two cases:
1 – She may be divorced when she is pregnant; this is a Sunnah divorce and is not bid’ah.
2 – She should be taahir (pure, i.e., not menstruating) and her husband should not have touched her (i.e., had intercourse with her), i.e., she should have become taahir following menstruation or nifaas (post-natal bleeding) and before he has intercourse with her. Talaaq in this case is in accordance with the Sunnah.
Fataawa al-Talaaq by Shaykh Ibn Baaz, 1/45-46
So long as he took her back during the ‘iddah, then she is still his wife, because the ‘iddah of a woman who is pregnant ends when she gives birth, and her husband took her back before she gave birth. Allaah says (interpretation of the meaning):
“And for those who are pregnant (whether they are divorced or their husbands are dead), their ‘Iddah (prescribed period) is until they lay down their burden”
This is the ‘iddah of the pregnant woman whether she is divorced or widowed. The husband should count this as one talaaq. And Allaah knows best.