Firstly:

Allah, Exalted is He, has decreed upon His creation both kawnī (universal) and shar῾ī (legal) rulings. Among these is His division of creation with respect to the gift of offspring: some are granted it, others are deprived. Those who are granted offspring may be given sons, daughters, or both, or may be limited to one type.

Allah, Exalted is He, says: “To Allāh belongs the dominion of the heavens and the earth. He creates what He wills. He gives to whom He wills female [children], and He gives to whom He wills males. Or He couples them—males and females—and He makes whom He wills barren. Indeed, He is Knowing and Competent.” [Al-Shūrā 49–50].

Given this divine division, the only proper stance is contentment, alongside pursuing lawful means. Whoever goes beyond this has transgressed, wronged, and deserves the consequence of sin and punishment.

Secondly:

The reality of motherhood is not confined to the outward image some may present—i.e., the mere union of a man’s sperm with a woman’s egg. This is but a tangible, material precursor aligned with the physical, animal nature of human bodies. True motherhood, however, is a continuous process, including pregnancy, childbirth, and nursing.

Allāh, Exalted is He, says:

“His mother carried him with hardship upon hardship.” [Luqmān 14].
“His mother carried him in hardship and gave birth to him in hardship.” [Al-᾽Aḥqāf 15]
“His bearing and his weaning [are] thirty months.” [Al-᾽Aḥqāf 15]
“Their mothers are none but those who gave birth to them.” [Al-Mujādilah 2]

All of these texts link motherhood to a continuous process: beginning with fertilization, extending through pregnancy, and concluding with childbirth.

Any other form of attributed motherhood is secondary, not genuine. This includes milk-motherhood (nursing) as in His saying: “And your mothers who nursed you.” [Al-Nisā᾽ 23]

Or maternal aunts functioning as mothers, as in the ḥadīth of the Prophet (peace and blessings be upon him): “The girl shall stay with her maternal aunt, for the maternal aunt is [the same as] a mother.” [Recorded by ᾽Aḥmad and Abū Dāwūd]

Thus, the mere mixing or meeting of reproductive fluids does not, from either a shar῾ī or customary standpoint, establish motherhood.

Thirdly:

It is not hidden what great harms lie in deeming this procedure permissible—harms that suffice for its prohibition. Among them:

• The trivialization of ᾽arḥām (wombs).
• Using the second wife as a mere tool for the first.
• Enslaving a part of a free woman through the marriage contract—since the contract gives the husband absolute usufruct over her private parts, not to anyone else!
• The possibility of disputes between the mother who gave the egg and the mother who used her womb, leading to corruption and discord.
• Ambiguity in matters of inheritance: does the child inherit from the egg donor or the womb bearer?
• Confusion in rulings related to male and female maḥārim (unmarriageable relations) between relatives of both wives. For example, if the child is attributed to the infertile first wife, he would be legally permitted to marry the sister or daughter (from another man) of the second wife who bore him—something that opposes sound human norms. It is not sufficient to argue that the solution lies in nursing (i.e., the second wife should breastfeed the child to establish foster relations), because milk may not be produced for any number of reasons. This then becomes a shift from one workaround to another.

Conclusion:

It is definitely impermissible to fertilize the egg of the first wife with the husband’s sperm and implant it into the womb of the second wife. Doing so is a clear sin, even if it does not constitute zinā (fornication). The child, by Shar῾ī ruling, is attributed to the second wife—the one who bore him.

Final Word of Counsel:

We must not oppose the will of Allāh through human endeavors. Rather, we utilize possible endeavors to uncover His will. Once we have knowledge of His will, we submit to it.

The ᾽asbāb (human endeavors) we employ must be consistent with the objectives of Sharī῾ah, its universal maxims, and its moral values. Using the womb of the second wife to facilitate the motherhood of the first is a form of ῾ubūdiyyah (subjugation) that is not permissible.

Widening access to such matters—matters that are restricted by both Sharī῾ah and sound custom—leads to grave corruption. We already witness the consequences in the permissive Western societies, which attempt to cloak their moral failures with talk of values and human needs.

If we open the door to such matters, perhaps a time will come when we begin implanting into animal wombs, replacing the human mother with a non-human one!!
What a big loss, then! To Allāh belongs the decree before and after.

Fatwā issued by Dr. Khālid Naṣr