Can delaying the fulfillment of a vow be a reason for delayed pregnancy
13-8-2015 | IslamWeb
Question:
Some years before I got married, I wanted to perform ‘Umrah, but I could not because I did not have a Mahram (permanently unmarriageable kin). I vowed that when I got married, I would perform ‘Umrah in the first Ramadan after marriage. When I got married, I told my husband about that, and he asked me to wait until we find a means to perform the Hajj since the Hajj is an obligation and is more important. What is the ruling, knowing that I have been married for three years, and I have not had children yet? Can failing to fulfill the vow be the reason for that? Please advise, May Allaah Reward you.
Answer:
All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
Whoever vows to obey Allaah Almighty and perform an act of worship seeking thereby to draw close to Him should fulfill his vow because the Prophet, sallallaahu ‘alayhi wa sallam, said: “If one vows to obey Allaah Almighty, he should obey Him.” [Al-Bukhari] It is disallowed to delay a time-fixed vow without a valid excuse. So you should hasten to fulfill your vow and offer expiation like that of breaking an oath, as we have clarified.
Concerning the delay of pregnancy, one of its reasons is committing forbidden acts and acts of disobedience because offspring is a form of provision. The Prophet, sallallaahu ‘alayhi wa sallam, said: “One may be deprived of provision because of a sin that he commits. Fate is only averted by supplication and lives are only prolonged by righteousness.” [Ahmad and others]
Al-Munawi 
said in Faydh Al-Qadeer:
"Some scholars said: "Know that some incidents might seem harsh while they actually involve kindness. For example, a slave may be deprived of provision because of the sins he commits. If the slave turns away from his Lord and gets preoccupied by the favors that He bestows upon him, then He deprives him so that he is frightened and deterred. He restricts for him the gates of sustenance so that he resorts to Him and heads towards Him with humble submission."
There is no doubt that failing to fulfill a vow and delaying it without a valid excuse is an act of disobedience that should be followed by repentance and regret. We have previously clarified some of the reasons that lead to deprivation of offspring and how to treat them.
You have to persistently adhere to repentance, supplication and frequent Istighfaar (asking for forgiveness). There is nothing wrong if you and your husband visit a specialized physician. Perhaps there is a problem with one of you. However, delay of pregnancy does not mean that you will never have children. Many spouses waited for more than ten years, then Allaah Almighty granted them children.
Allaah Knows best.