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Why does progesterone help prevent another ovulation during pregnancy?

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Diagram comparing reproductive pathways: arrows show sexual reproduction forming a diploid zygote from oocyte and sperm, haploid parthenogenesis forming a haploid individual, and two types of diploid parthenogenesis-automixis and apomixis-both resulting in diploid individuals. Symbols indicate haploid and diploid stages. — Animal reproductive system The process of sexual reproduction and several forms of parthenogenesis.

Progesterone prevents further ovulation during pregnancy primarily through its feedback action on the pituitary gland.12

By suppressing the release of specific hormones from the pituitary—namely the follicle-stimulating hormone and luteinizing hormone—progesterone effectively halts the cycle that would otherwise lead to the maturation and release of another egg. This process, often occurring in conjunction with estrogens, ensures that the reproductive system remains focused on the maintenance of the existing pregnancy and the undisturbed development of the fetus.123