The first part of pregnancy can be tough because while you probably feel pregnant, you might be keeping your pregnancy to yourself. Maybe you can’t keep food down or keep your eyes open thanks to fatigue, but those symptoms aren’t always visible, so your friends and coworkers are just wondering what is going on. On the other side of the coin, you may not be feeling anything like that, which could make you worry that the pregnancy is not going as it should.
Either way, you might have questions about when the outward manifestation of your physical condition in the form of a beautiful baby belly will appear. Or maybe you’re hoping to keep your pregnancy private and are concerned that a growing belly will give you away. In general, the arrival of the baby bump can be different for everyone, just like each individual experience of pregnancy is different.
How Baby and Your Body Grows
You probably already know that baby starts out as a tiny fertilized egg—smaller than the period at the end of this sentence. And baby stays small for quite a while; it will only be the size of a small plum at the end of week 12 of pregnancy. While baby grows rapidly, it still weighs less than half a pound at 18 weeks of pregnancy. 
In terms of belly size, your growing uterus doesn’t even leave your pelvis until around week 12 or 13 or the end of the first trimester. At that point the womb is about the size of a grapefruit. Starting around week 18 of your pregnancy, your care provider will start to measure your fundal height, or the distance from your pubic bone to the top of your uterus or fundus. This distance is a good proxy for the size of your uterus and thus how baby is growing. From 18 or 20 weeks on, the number of centimeters from your fundus to your pubic bone is usually about the same as the number of weeks in your pregnancy. For instance, your fundal height will measure about 30 centimeters at 30 weeks. 
Early Baby Bumps
Some people’s bodies reveal their pregnancies early on in the form of a growing tummy. If you are of shorter stature, your belly will likely be bigger sooner because your smaller torso can fit in less baby before the belly grows out instead of up into your abdominal cavity. And if this is not your first pregnancy, it is likely that your belly will “pop” a bit sooner. Subsequent pregnancies tend to show earlier, perhaps because the muscles and ligaments are already relaxed from having grown a baby before. Many pregnant folks start wearing maternity clothes much earlier in subsequent pregnancies because they feel so much more comfortable.
Late Baby Bumps
Conversely, some baby bumps make their appearance later or are not ever apparent. Just like folks of shorter stature might have baby bellies sooner, tall people, who tend to have larger torsos and thus more room for baby to grow, will likely show later. Likewise, pregnant people with bigger bodies may not have a distinct baby bump until later in pregnancy. As a general rule, your belly will likely pop later if this is your first pregnancy. Finally, if you have hyperemesis, or some other medical condition that affects weight gain during pregnancy, your baby bump might be delayed in making its appearance.
Regardless of the timing of your bump’s appearance, you might have feelings about it. And those feelings can be exacerbated as you attempt to cope with comments about how your body looks. Everyone—whether they are strangers or friends—likes to voice their opinions about the state of pregnant people’s bodies, and that can be really annoying.
Some of the worst comments focus on the size of the bump. But people who don’t look at pregnant bellies for a living (like your doctor or midwife) generally know almost nothing about the size that a bump “should” be. It’s not uncommon for one person to remark that your bump is huge for however far along you are and then later the same day, someone else might comment that your belly is “tiny.” There are some ideas about coping with rude comments in this blog post, but it might also help to remember that everyone’s baby bump is different, and that’s okay.