Utility Magic: Increase Fertility
Components: V, S, M (a carved totem of a baby worth at least 10 gold)
You touch a willing humanoid, granting it an increase in fertility until the following day; while conceptus from intercourse during that time is not completely certain (90% chance), it is much higher from the results of this spell (and will be nearly certain if both partners are enchanted with this spell, 99% chance), so long as both partners are normally capable of conception (eunuchs, post-menopausal, and the like will not benefit from this spell).
The carving is consumed during the course of the casting. In many societies, there are great superstitions surrounding the precise details of the carving, with many giving strong credence to beliefs that the precise materials used will lend itself to a particular end for the child (i.e. pearl eyes for the carving are believed by some to guarantee that the child will have superior eyesight, while other cultures believe that it will predispose the child to a life at sea, or the use of mahogany or oak or bone will have other effects). While many wizards who study this have found no such link, that does not prevent the fussing from friends, family, and other interested parties (more than one royal has had a diplomatic crisis resulting from their selection of materials for the spell material for a potential heir).
This spell can be cast at higher levels for greater effect; at 4th level, it allows males of ovipositioning races (aarakocra, dragonborn, gith, etc) to impregnate females of in vivo races (most other humanoids), with the resulting children being of one race or the other. At 5th level, it allows for in vivo males to impregnate females of ovipositioning races, resulting in the laying of an egg as per normal, but with the resulting children being of one race or the other (meaning that, yes, it is possible for a dragonborn woman to have a human baby born from an egg).
Dragons shapeshifted into humanoid form have no need of this spell, as their innate magic will overcome such piddling barriers as being of entirely different species and creature types.
Spell Lists: Bard, Cleric, Druid, Paladin, Wizard
Development Notes: Another piece of utility magic that came about from pondering "Okay, what are the sorts of things that people historically went to faith healers, herbalists, and the like for, and which we use extensively when science was able to provide?" And the answer is: control over our own fertility. Of course, once I started writing it out and thinking of the little carved baby statue that gets used as a consumable component, I realized that I'd hit upon an incredible vein of worldbuilding potential. Just imagine the traditions, folklore, superstitions, and more that would come from that little statuette's construction; you'd have crafters whose entire careers would be spent making them. They would be wedding gifts; parents would "hint" about wanting grandkids. Books would be written on the various intricacies of their construction; the fact that, mechanically and looking from outside of the setting, we know that these have no effect would not matter to societies within that setting. It would be popular on levels we associate with astrology and the like IRL.
And that sort of rich vein of cultural folklore and such can have such an effect on the vividness of a fantasy setting, at least in my opinion.