Srimad-Bhagavatam: Canto 6 - Chapter 1 - Verse 4
यथा धानासु वै धाना भवन्ति न भवन्ति च ।एवं भूतानि भूतेषु चोदितानीशमायया ॥ ४ ॥
yathā dhānāsu vai dhānābhavanti na bhavanti caevaṁ bhūtāni bhūteṣucoditānīśa-māyayā
When seeds are sown in the ground, they sometimes grow into plants and sometimes do not. Sometimes the ground is not fertile, and the sowing of seeds is unproductive. Similarly, sometimes a prospective father, being impelled by the potency of the Supreme Lord, can beget a child, but sometimes conception does not take place. Therefore one should not lament over the artificial relationship of parenthood, which is ultimately controlled by the Supreme Lord.
Mahārāja Citraketu was actually not destined to get a son. Therefore although he married hundreds and thousands of wives, all of them proved barren, and he could not beget even one child. When Aṅgirā Ṛṣi came to see the King, the King requested the great sage to enable him to have at least one son. Because of the blessing of Aṅgirā Ṛṣi, a child was sent by the grace of māyā, but the child was not to live for long. Therefore in the beginning Aṅgirā Ṛṣi told the King that he would beget a child who would cause jubilation and lamentation. King Citraketu was not destined to get a child by providence, or the will of the Supreme. Just as sterile grain cannot produce more grain, a sterile person, by the will of the Supreme Lord, cannot beget a child. Sometimes a child is born even to an impotent father and sterile mother, and sometimes a potent father and fertile mother are childless. Indeed, sometimes a child is born despite contraceptive methods, and therefore the parents kill the child in the womb. In the present age, killing children in the womb has become a common practice. Why? When contraceptive methods are taken, why don’t they act? Why is a child sometimes produced so that the father and mother have to kill it in the womb? We must conclude that our arrangement of so-called scientific knowledge cannot determine what will take place; what is enacted actually depends on the supreme will. It is by the supreme will that we are situated in certain conditions in terms of family, community and personality. These are all arrangements of the Supreme Lord according to our desires under the spell of māyā, illusion. In devotional life, therefore, one should not desire anything, since everything depends on the Supreme Personality of Godhead. As stated in Bhakti-rasāmṛta-sindhu (1.1.11): “One should render transcendental loving service to the Supreme Lord Kṛṣṇa favorably and without desire for material profit or gain through fruitive activities or philosophical speculation. That is called pure devotional service.” One should act only to develop Kṛṣṇa consciousness. For everything else, one should fully depend upon the Supreme Person. We should not create plans that will ultimately make us frustrated.