Newborns spend most of their time doing three things: eating, sleeping and soiling diapers. When your baby arrived, you might have thought that’s all there was to expect as far as infant care went—until baby started doing some unexpected (and honestly pretty weird) things.

If you’ve panic-Googled things like “What causes newborn acne?” or “Why does my baby have hiccups?” or even “Can newborn girls have a period?,” you’re not alone. As strange as these things may seem, for the most part they’re totally normal reflexes or reactions for babies two months old and younger.

Here are 11 weird things your baby might do in their first several weeks of life, and why.

Get the hiccups

Hiccups are one of the most common reflexes in newborns, starting even before birth. You may have felt your baby hiccuping when they were still in the womb; it’s the same reflex your baby experiences now (and will for the rest of their life).

Your newborn is likely getting cases of the hiccups “due to immaturity and irritation of the nerve that goes down the diaphragm, which can sometimes be triggered by swallowing or drinking formula or breast milk,” says Dr. Mona Amin, pediatrician and host of The Pedsdoctalk Podcast. This is the same reason all mammals get hiccups, but babies will get them more often until their system matures a little more.

But unlike when other people get hiccups, with babies “you don't need to do anything,” Dr. Amin says. “Avoid startling them or giving them water. You don't need to treat as you would for an adult. They will go away.”

Develop acne

Not all newborns experience “baby acne,” and those that do can have it in all different amounts and locations on their bodies. If your baby ends up with little red bumps on their face, neck, back or chest, try not to worry. It’s probably not an allergic reaction or a sign of infection. Hormones are the most likely cause of pimples on otherwise flawless newborn skin. Specifically, they’re leftover pregnancy hormones that were transferred into baby’s bloodstream before birth.

And as much as you want it to go away quickly (and in time for those newborn photos), don’t try to treat a baby’s acne like you would a teenager’s or an adult’s. Baby skin is really sensitive, and most skin care products can irritate their skin and potentially make the acne even worse. Besides, “it will usually go away on its own,” Dr. Amin says. “If it’s severe or lasts beyond two months, speak to a pediatrician, as we sometimes do recommend topical ointments to prevent scarring.”

In the meantime, you can use a gentle baby shampoo and body wash—it may not do anything to clear up the acne, but it won't make it worse, either.

Breathe rapidly

This is baby’s first time breathing air, so they might not be perfect at it yet. While most of their breathing will seem normal, “sometimes, periodic breathing happens, which is when a baby breathes fast and then slows,” Dr. Amin says. It may seem like hyperventilating, but it’s not caused by stress or panic—and it won’t last forever. “Periodic breathing happens due to immaturity of the respiratory system,” Dr. Amin says. “It’s not dangerous or harmful and improves as they get older.”

It’s typically nothing to worry about, but if your baby’s rapid breathing is accompanied by changes in skin color or if their ribs are moving a lot (as opposed to belly breathing), that’s when it’s time to contact your pediatrician, as it may be a sign of respiratory infection.

Have dry, flaky skin

“Dry, flaky, or peeling skin is common,” Dr. Amin says. “Babies were in a water environment for nine months, and they came out dry!” As your baby’s skin adjusts to the new environment, it may get dry and even flake or peel off in small pieces. The dryness will go away on its own within the first few weeks, and it probably doesn’t bother your baby. But if it bothers you, you can try one of our favorite baby lotions to help smooth out baby's skin.

Grunt while asleep

You knew your newborn would cry (a lot), but you might not have known about the other sounds they’d make—like grunting and snorting. It’s especially common when baby is sleeping, and it’s likely due to the smallness of their airways where mucus can get trapped more easily, an immature respiratory system or acid reflux.

“It’s nothing to be worried about,” Dr. Amin says. However, “if baby is awake and in distress, call your child's doctor. Do you see their ribs moving quickly and do you notice a color change in them? If not, no need to worry.”

Sneeze

Don’t break out the hand sanitizer just yet. A newborn with a case of the sneezes but no other symptoms probably isn’t sick. “Babies sneeze a lot!” Dr. Amin says. “Babies sneeze as a protective mechanism to keep the nasal passages free of irritants.” Your newborn’s nose is encountering a lot of new things outside the womb, from dust to pet dander to household cleaners, and to a sensitive system like your baby has, lots of things might be even slightly irritating. So if your baby is sneezing up a storm but doesn’t have a cough, fever or any trouble sleeping, rest assured it’s just their system working to keep airways free and clear.

There’s not much you need to do to assist, but “if your baby seems congested and bothered, use saline and a suction tool,” Dr. Amin says. “Otherwise, monitor them. Remember, fever over 100.4 is always worthy of a note to your child's doctor.”

Twitch or make jerking movements

Sudden unexplained twitches in a newborn can be startling, but thankfully it’s common and usually not a cause for concern. “This has to do with the immaturity of their nervous system that improves as they get older,” Dr. Amin says. “You won’t see jerky movements forever!” Until baby’s nervous system is better developed after a few months, they may have trouble coordinating muscle movements, resulting in sudden jerks of their arms and legs.

While occasional quick twitches or shakes are normal, more frequent or prolonged twitching may be a sign of something serious. If your baby makes rhythmic jerking movements accompanied by eye rolling, or if their twitching doesn’t stop when you apply pressure, call your baby’s pediatrician right away as it could be a sign of seizure.

Tense their muscles and clench their fists

You might be surprised to learn that newborns have a tough time relaxing. Literally. “Babies are in the fetal position in the womb for nine months,” Dr. Amin says, “so you may notice that they are a little tense in the first few weeks as their nervous and muscle systems develop.” If you were stuck in the same position with limited room for that long, you’d feel a little tensed up too. Baby’s arms and legs should be fully relaxed by the time they’re two to three months old.

Newborns also keep their fists clenched most of the time, sometimes even during sleep when the rest of their body is relaxed. There are a couple of reasons for this:

The palmar reflex, which causes babies to involuntarily grip anything placed in their palm (like your finger) and is considered a precursor to baby’s future fine motor skills. This reflex will disappear sometime between four and six months old.
Hunger. Your baby’s fists may get tighter as they get hungrier and will relax as they eat, so pay attention to this cue when you’re wondering if it’s feeding time.

Cross their eyes

If you think your baby might have been born with crossed eyes, or if you notice their eyes drifting asymmetrically during the first few weeks, chances are that’s not actually the case, and their eyes really are symmetrical. Babies may appear to have crossed eyes for a few reasons:

Lack of coordination in eye muscles. Just like the rest of their muscles, the ones that control baby’s eyes will need a little time and practice to learn to work together, especially when it comes to focusing. As your baby tries hard to focus their vision on an object, you might see their eyes drift to either side independently of each other, then go back to normal. You can expect baby’s eyes to coordinate better around two months old.
Pseudostrabismus, or eyes that appear permanently crossed but actually aren’t, happens when babies have a flat, wide nasal bridge that creates a small fold in the inner corner of their eyelids, causing their eyes to seem off-center when looking straight ahead. Think of it as an optical illusion (pun intended). To see your baby’s real eye alignment, take a flash picture of them looking at the camera straight-on; if the flash’s reflection is in the center of both pupils, their eyes are centered. If the flash’s reflection appears off-center in either pupil, your baby’s eyes are indeed crossed, and you should contact their pediatrician to have further testing done. Pseudostrabismus can last anywhere from six months to the rest of their life, depending on how their facial features develop.

Sleep with their eyes open

Everything on this list might be unexpected for new parents, but this one can be downright unsettling to see (especially on a video monitor in the middle of the night). Thankfully, “partially or fully open eyes during sleep is actually very common,” Dr. Amin says. “The medical term for it is nocturnal lagophthalmos.” The most likely causes are:

Entering rapid eye movement (REM). Baby’s nervous system isn’t fully matured yet, so it may struggle to coordinate all the muscle movements of REM, including keeping the eyelids closed.
Genetics. If either parent sleeps with their eyes open, even just occasionally, there’s a good chance baby will too.

You might see baby’s eyes moving rapidly, or their eyes may be completely still, depending on whether they’re in REM sleep. Either way, it’s totally normal and usually completely harmless, so don’t worry about trying to close baby’s eyes and risk waking them up. “Unless your baby is experiencing dry or red eyes as a result, there is no need to take action and it should go away over time,” Dr. Amin says. She recommends keeping baby’s room dark and using a humidifier to prevent dry eyes, though “it doesn’t hurt to mention this to your clinician, especially if your baby is experiencing other symptoms.”

Have their first “period”

We may have saved the weirdest for last. What could be more unexpected than noticing your baby girl getting her first menstrual cycle at two days old? But just like everything else on this list, it’s a completely normal and harmless thing for newborns to experience.

Although it can look like it, newborn vaginal bleeding isn’t true menses because baby hasn’t reached puberty (so don’t panic). It’s called “false menses,” and it’s caused by exposure to pregnancy hormones in the womb.

During pregnancy, estrogen levels are especially high, and baby is exposed to those high levels for nine whole months. But once the umbilical cord is cut, all of that extra estrogen is cut too, mimicking the natural decline in hormone levels that triggers the onset of bleeding in regular menstrual cycles.

False menses typically starts within the first week after birth (as early as two days old), lasts anywhere from one to four days and should only produce a light amount of vaginal bleeding and/or pink-tinged discharge. Call your baby’s pediatrician if newborn vaginal bleeding occurs after the first two weeks, lasts longer than four days or is heavier than a light period.