How to determine the sex of an unborn baby?

Question

Note: The subject of this question may be sensitive to some readers, so I request answers to be tactful and stay strictly in the scope and context of Dungeons & Dragons RPG.

We have a human female NPC who is pregnant in our campaign. Most importantly we'd like to find out the sex of the baby. Other stuff like, is it twins/triplets, is the father who we think it is (a human too), and what the "race" of the baby is (I mean, it could be a tiefling even if both parents are human), is interesting bonus information.

What methods (probably spells and magic items, maybe a medicine check somehow) are available in the official books?

I've been thinking of an (ab)use of Locate Creature spell, but it seems a bit iffy to consider an unborn baby boy/girl as "the nearest creature of a specific kind (such as a human or a unicorn)"...

I'm only interested in strictly 5e answers.

Answer 1

General note

The inside of the uterus during pregnancy is a closed environment. It has total cover from everyone, except for the pregnant woman, because the surface of it is part of her body. Therefore a lot of this becomes easier if she can cast spells herself. That might be hard to arrange, especially for the higher-level spells. If you can make her a spellcaster (it's unclear what kind of training or initiation that requires for an NPC), she can use spell scrolls.

Visual divination spells

Scrying almost surely works, since it lets you directly observe a creature. Since familiarity with the subject makes it easier, this would be a good one for Mom to cast herself--you don't get much more familiar than that. It is unfortunately fairly high level.

Clairvoyance may work, since you're allowed to place the sensor in a location that's out of sight but obvious. (This appears to be an exception to the clear-path rule; the examples include "behind a door" and "around a corner".)

The catch here is that the lack of a light source. If Mom can cast light then that's easy. Otherwise I'd start by trying dancing lights, under the theory that the lights are intangible and can pass right through her body. (They have to be conjured out in open space, but after that only have to remain in range.) This is convenient because you can move the light around as needed.

If it turns out the lights can't pass through, then trans-cervical illumination with daylight is the next least invasive option. Any high-powered cleric-midwife would be able to get this into position, and would likely have the spell prepared already.

Arcane eye, unlike the other options, has darkvision. It might work if Mom casts it herself (depending on how literally you take the "hovering in the air" part) but can't pass through solid barriers.

General divination spells

Commune is the easy option.

Augury is harder to justify. You'd need a contrivance like "In ten minutes I'm going to meet with the Duke of Florin and promise this child in marriage to his infant daughter once they come of age. For this to work out well for me, the child must be a boy." And then the joke's on you when it turns out that the positive outcome is reforming Florinese succession law to allow same-sex marriage, or learning that the Duke secretly has twins.

Getting into the Border Ethereal

You can do this with a spell like blink or etherealness. From the Ethereal Plane, you can pass through and dimly see creatures in the Material Plane, without disturbing them. The images aren't terribly clear, but you know, ultrasound isn't very clear either and an experienced operator can still figure a lot out from it.

Cheater options that shouldn't work

Mirror image creates an image exactly duplicating you. It's unclear if this includes internal organs, but if it does, you can stick your head inside the intangible image and have a look-see. I'm skeptical of this because it's an illusion spell, and it's most consistent to play those as only representing what's in the caster's mind (you can't look behind a door by casting a minor illusion of "a hole through the door", because you don't know what that would look like). It is clever, though.

Glyph of warding set to cast, say, light on "male creatures" might work but the use of glyph of warding as an "everything detector" is pretty cheaty. I tend to play it as being able to perceive only what its caster would be able to perceive from the same location, just because otherwise there are no limits on it.

Answer 2

There's not an awful lot of official options, because this isn't really something that comes up much in an adventurer's life.

If this is a plot significant question, then I would personally suggest adding a plot-based resolution to it. Something like "find the legendary midwife of the gods who can tell all these thing at a glance."

But, if you're just a player, and you're stuck with official player options:

A medicine check might work (ask your DM), but there's no real basis in reality. It took the development of ultrasound in the real world before telling the sex of an unborn child became a thing. (And it's still wrong sometimes).

So you're probably in the realm of divination magic.

You'll probably want to use Commune and directly ask a deity or divine messenger. That requires a 9th level caster and gives you 3 reliable yes-or-no questions per day. They'll probably know these things if they're in any way related to the subjects of life, fertility or community or if the NPC is a follower of the same or a closely related deity.

If the child is close to being born, you could also try Divination, which only requires a 7th level caster, but requires you to describe something that happens in the next 7 days.

If you've got a Wizard in the group, you could also try Contact other Plane to try and chat with a deity that way, but it might make you go crazy. Otherwise, same rules as Commune apply.

Based on the comments, I'm going to add Augury to the list. It requires some buy-in from your DM, since it requires you to specify an action you're going to take in the next 30 minutes and it only answers whether you'll get good results or bad results, but if you can convince your DM that buying a birth-gift based on the gender is a really bad thing, Augury might tell you it is Woe to buy a pink dress for the new baby. (But the DM might as easily decide that you'll succeed at buying the thing and how the mother will eventually react is outside Augury's prediction range.)

Answer 3

I'm not a doctor, and I don't play one in RPGs...

...However...

There are a few, off-the-wall, ideas that may work, depending on the DM. Please remember that even in this modern world with ultrasound and x-rays, they still get surprised now and then.

Wish

Because Wish is the cure-all of solving non-RAW problems.

Scrying

You can see and hear a particular creature you choose that is on the same plane of existence as you...the spell creates an invisible sensor within 10 feet of the target. You can see and hear through the sensor as if you were there.

So you could attempt to scry on your unborn child and see for yourself. If there are twins, you would still see both of them.

Divination Wizard

While nothing RAW about the class goes to knowing gender in the future, I would see this as a skill they could do. Perhaps as a new option for the "The Third Eye" feature.

Warlock Invocation; Ghostly Gaze

As an action, you gain the ability to see through solid objects to a range of 30 feet. Within that range, you have darkvision if you don't already have it. This special sight lasts for 1 minute or until your concentration ends (as if you were concentrating on a spell). During that time, you perceive objects as ghostly, transparent images.

This would be the most "reasonable". It would not be a stretch to say that for the minute, the caster can see inside the mother and see the "ghostly" image of the baby/babies. Now technically, the description says "solid objects", and "objects" is a defined term in 5e, of which a living mother is not. But you could made a pretty good case to the DM.

And for items...

Danoth's Visor; from EGW

As a bonus action, you can speak a command word and use the goggles to see into and through solid matter. This vision has a radius of 60 feet and lasts for 1 minute. To you, solid objects within that radius appear transparent.

Same as the Warlock Invocation.

Ring of X-ray Vision

While wearing this ring, you can use an action to speak its command word. When you do so, you can see into and through solid matter for 1 minute.

Same as the Warlock Invocation.

I'll also add a macabre option, but would fit well within a fantasy campaign:

* Cast Astral Projection on the mother, rendering her "unconscious and in a state of suspended animation." Basically, anesthesia.
* While separate from her physical form, cut her open as if doing a cesarean section and inspect the baby/babies
* Cast Cure Wounds, Heal, Regenerate, what have you, to fix the wound
* Bring her consciousness back unaware of what happened to her body

Answer 4

Visit a friendly Sphinx's lair.

The sphinx has the following lair action that it can use once per long rest:

The flow of time within the lair is altered such that everything within moves up to 10 years forward or backward (sphinx’s choice). Only the sphinx is immediately aware of the time change. A wish spell can return the caster and up to seven other creatures designated by the caster to their normal time.

The mother sends someone else into the lair while she is pregnant, and then simply leaves and comes back later after the birth. The person who goes into the lair goes forward in time by however long it would take the birth to happen. This is up to the sphinx, but it's technically possible. The person who went forward in time then checks what the sex of the child is, likely by just asking the future version of the mother. The sphinx then takes a long rest, and returns the person to their original time. The person then relays the sex of the baby to the present version of the mother.

Alternatively, the mother could visit the sphinx and ask the question, and the sphinx could just tell her to return to the sphinx on a specific date. The the mother leaves the lair, and the sphinx goes to the specified date and asks the mother itself. Then it takes a long rest, returns to the present, and reveals the information to the mother, bypassing the need for a third creature.

Answer 5

For a very macabre option (in spoiler tags for sensitive readers):

Kill the mother.

If the mother or the baby's life are important, but trauma isn't a concern, you can do this and bring them back within a minute with a 3rd level Revivify. If trauma is a concern, as wakinadivellir mentioned, players can try this attempt and cast Modify Memory to erase the trauma.

Answer 6

There Are A Few Lower Level Options (My favorite is Glyph of Warding)

Before we get into the answer, let me point out that this question is complicated by several details. First, an unborn fetus is likely considered to have "total cover," and thus is not a valid target for many spells. Also, there is RAW support for the idea that in DnD, gender and sex may include other categories than "male and female." On page 121 of the PHB, it states:

You don't need to be confined to binary notions of sex and gender.

So depending on your DM, it's entirely possible that this question could be harder to answer than it initially appears. But there are options available to a clever player or DM which could at least give you hints at the sex of the anticipated new arrival.

Augury Is Viable, But Unclear

Naturally, spells like "Wish" or "Commune" could be good options (the pros and cons of these are mentioned in detail in other answers). But these spells require higher level casters which you might not have access to. If you're hoping to use the fewest resources possible and get some viable information, your best bet is likely the 2nd level spell Augury.

Augury is a Ritual spell, so provided you have access to a class with Ritual casting you will not even need to spend a spell slot. And since its target is "self," you won't have to worry about the fetus having total cover. There are two major limitations of Augury. First, you must inquire about a course of action you plan to take in the next 30 minutes. Second, you only get vague answers: essentially "good," "bad," "mixed," or "neither good nor bad."

You could take your chances with Augury, perhaps choosing the action under investigation to be "Buying a girl's blouse for when this baby is born." You could interpret a "good" result as saying you've correctly guessed the fetus's sex, and a "bad" result as saying you haven't. However, it's possible the DM will consider an atypically colored garment to be "neither good nor bad" for the purposes of the spell. And even if you get a "good' or "bad" result, it's worth noting that the DM doesn't have to tell you why a specific action yield that prediction in an Augury reading. You might get a result of "bad" based on buying a "girls'" outfit because the outfit is shoddily made, or the parents are allergic to the fabric. You wouldn't know whether or not the assumed sex of the wearer is related to Augury's outcome.

Glyph of Warding is likely your best bet

The spell Glyph of Warding's has an option to create a Spell Glyph. This will permit you to have a spell of your choosing be cast under specific circumstances, usually when a creature touches or approaches to within a certain distance of the Glyph. (NOTE: An errata clarified that this spell does not need to be harmful). According to Glyph of Warding's description (PHB, p. 246, bold added):

You can further refine the trigger so the spell activates only under certain circumstances or according to Physical Characteristics (such as height or weight), creature kind (for example, the ward could be set to affect Aberrations or drow), or Alignment.

You could set up a Glyph of Warding to cast a visible but harmless spell (such as Dancing Lights) if a humanoid male weighing less than 20 pounds was within 10 feet of the Glyph, then ask the pregnant mother to approach. According to the rules of Spell Glyph (ibid):

If the spell has a target, it Targets the creature that triggered the glyph. If the spell affects an area, the area is centered on that creature.

Since the fetus is behind total cover, it is essential that the spell stored in the Glyph does not have a target, or it will fail: again, Dancing Lights would be a valid example. You also do not have to worry about the area being "centered" on the fetus and thus hiding the effect within the womb, because the rules for casting spells with an area of effect state (PHB, p. 204):

If you place an area of effect at a point you can't see and an obstruction, such as a wall, is between you and that point, the point of origin comes into being on the near side of that obstruction.

Thus, the dancing lights will have an area of effect centered outside of the expectant mother, and will be visible. Note that the fetus was also not the "target" of the spell Glyph of Warding itself: it is merely the source of its activation. So as long as your DM considers the fetus to count as "a humanoid" in this setup, you will know whether or not the fetus's sex is male by whether or not this spell activates.

A few caveats: first, note that Glyph of Warding is not without costs. You'd need to spend at least a 3rd level spell slot, and also 200gp worth of powdered diamond which the spell would consume: a hefty cost at lower levels. Also, note that the Glyph would only be able to give binary answers in the form of activating or not: if you wanted to get a different outcome for a male or female fetus, you'd need to cast multiple instances of this spell with different triggers. And that may be a wise idea (in addition to letting you ascertain other details, such as the fetus's race), because if the spell does not activate, it is difficult to be sure why. For example, it might have activated because the spell does not consider an unborn fetus to be a "humanoid," or "male" yet (perhaps it has not developed enough to fit the definitions of either the spell would use). So the precise wording of the trigger may take some trial and error.

However, of your various options, Glyph of Warding is likely one of the best. It does not rely on the ability to predict the future, as it is assessing the present status of the fetus, and is capable of assessing the physical characteristics you're interested in.

A word about the future

A major advantage of Glyph of Warding is that it does not rely on abilities that predict the future. It would only be able to assess the current qualities of the fetus, and would not rely on what the future might hold.

That is significant, because in DnD neither sex nor gender is guaranteed to be fixed. Spells like True Polymorph and Wish allow any number of permanent changes to a creature's body, and even lower level spells like Alter Self might permit such changes temporarily.

I'm partly pointing these things out to clarify why divination magic might be unreliable in this case. But I'm also pointing it out to urge you to consider the possibilities of the fetus's ultimate fate. I do not know why it is important to your game that you find out the current sex of this fetus: maybe there is a prophecy, or laws of inheritance and/or succession that you're concerned with, or other such weighty reasons. But I urge you to keep an open mind.

Speaking purely based on the rules of the game that we are all playing: whatever the fetus is, that is not necessarily what they will ultimately be.