There is no hadeeth which says that having an easy pregnancy is a sign of special mercy from Allah

Praise be to Allah.

We have not found anything in the saheeh Sunnah or the reports from the Sahaabah and Taabi‘een to indicate that an easy pregnancy is one of the signs of special mercy from Allah, may He be exalted, to a woman. That is one of the matters of the unseen regarding which we must adhere to what is mentioned in the texts and reports, and not attribute any such thing to the Prophet (blessings and peace of Allah be upon him) unless we are certain of it and that it is saheeh. Allah, may He be glorified and exalted, says (interpretation of the meaning):

“And follow not (O man i.e., say not, or do not or witness not, etc.) that of which you have no knowledge (e.g. ones saying: "I have seen," while in fact he has not seen, or "I have heard," while he has not heard). Verily! The hearing, and the sight, and the heart, of each of those you will be questioned (by Allah)”

[al-Isra’ 17:36]. 

Moreover, the mercy of Allah, may He be exalted, may be in wellbeing, but it may also be in trials and tests, according to the knowledge and wisdom of Allah, may He be glorified and exalted. It was narrated from Muhammad ibn Khaalid, from his father, from his grandfather – who was a companion of the Messenger of Allah (blessings and peace of Allah be upon him) – that he said: I heard the Messenger of Allah (blessings and peace of Allah be upon him) say: “If a certain status has previously been decreed by Allah for a person, and he does not attain it by his deeds, Allah afflicts him in his body or wealth or children.”

Narrated by Abu Dawood in as-Sunan, no. 3090. Classed as saheeh by al-Albaani. This hadeeth indicates that if a woman is tested with difficulty and hardship in pregnancy, that may be a sign of Allah’s mercy towards the woman and of what she will have with Allah of reward and great status, especially if we remember the hadeeth of the Prophet (blessings and peace of Allah be upon him) in which he said: “There is no calamity that befalls a Muslim but he is expiated thereby, even a thorn that pricks him.”

Narrated by al-Bukhaari (5640) and Muslim (2572). 

Thus it is clear that whoever wants to attain the mercy of Allah, may He be exalted, let him be patient at the time of calamity and let him be grateful at the time of blessing, for in that case he will be in a very good state and will not be distracted by thinking about what Allah, may He be exalted, intends by this calamity, for that is one of the matters of the unseen of which he has no knowledge, but by being grateful and showing patience, he will attain the mercy and good pleasure of Allah. 

Sufyaan ath-Thawri (may Allah have mercy on him) said: 

There is no one who understands Islam but he regards calamity as a blessing, and ease as a calamity.

End quote from Hilyat al-Awliya’ (7/55). 

One of the earlier generations said: 

Be content with Allah in all that He does to you, for He does not withhold from you except in order to give you, and He does not put you through trials except in order to bring about your well-being, and He does not cause you to be sick except in order to heal you, and He does not cause you to die except in order to bring you back to life. So beware of failing to be content with Him even for a moment, lest you be deprived of mercy.

End quote from Madaarij as-Saalikeen, 2/216 

But if there is some symptom of illness that prevents you from having another child, that does not indicate that you are a bad woman or that you have been cast away from the mercy of Allah – Allah forbid. Rather that is a common occurrence and there is no blame on you. “and [Allah] has not laid upon you in religion any hardship”[al-Hajj 22:78]. But we also think that the difficulty and hardship that you are facing at present mean that this is not an appropriate time to take such a decision. How many women have thought in such situations the same as you are thinking now, but when Allah made the birth easy for her and she had rested for a while after that hardship, she once again began to long for pregnancy and childbirth, and to raise little ones. Perhaps if Allah makes the birth easy for you – in sha Allah – and you rest for a while after that, maybe Allah will help you with another pregnancy. But it is too early to make such a decision now 

For more information, please see fatwas no. 161204 and 150171

And Allah knows best.