I snorted when a book I was reading admonished against telling a pregnant woman she was “fat.” Yes, of course. That’s probably a bad call. Instead, however, it recommended that rather than the word “fat,” you kindly refer to the additional weight gain as “Maternal Storage Tissue.”

Because yes, that’s what every woman wants to hear.

“Damn, your maternal storage tissue is looking finnnneee.”

No thank you.

My body is getting bigger, and I think it’s beautiful.

Women gain 25 to 35 pounds (according to American standards, and for many woman, it can vary even more) for each pregnancy. The weight is divided up into different places: our blood volume nearly doubles, we carry more fluid (both inside our uterus as amniotic fluid as well as throughout our bodies), we create an entirely new organ from scratch (the placenta), and we build a human being (who weighs roughly 7-8 pounds, again with variation depending on your kid).

Also, our breasts swell up quite a bit – they can double in size in the first part of pregnancy, and then double again once you deliver your baby and if you begin breastfeeding. I keep buying new undergarments online because I keep outgrowing them! (One downside is that no, retargeted advertising, I do not need to see pictures of underwear all over the place while I’m working during the day.)

In addition to this fluid and human gain, we also gain fat storage deposits. Beautiful, gorgeous, lovely lady lumps.

I weigh myself each week (top of the morning, after my morning pee), to get a reading on how my body is changing from a mass standpoint. What surprises me, however, is how everything is shifting and changing beyond just my belly and boobs (my “front bumps,” as I like to joke).

I pulled on an old pair of jeans to see how they would fare if I left the top unbuttoned — there’s a fancy pregnancy trick where you can loop the top button together with a hairband or rubber band to make your pants fit longer) — but surprisingly, it wasn’t my belly that caused them to feel tight. I got them up about mid-thigh, and my jeans said NOPE, not going to happen.

Apparently my thighs are building out some maternal storage tissue and my tush is also starting to gain a bit of weight.

Here we go, mama.

Another area that surprises me is the bottom of my bra line — where the bottom of a sports bra hits, or where the bra clasps together. I thought that my rib cage would stay fairly consistent in size, even if my belly and breasts swelled outwards. Apparently, however, as a baby grows inside of you, your stomach gets pushed upwards and your rib cage can expand outwards to accommodate the extra space. Bras that have a single-fasten strap or a fixed elastic band no longer fit, because I’m bigger around… everywhere.

When I’ve watched friends go through pregnancies in the past, I watch them in the year before the birth and in the year after. Everyone seems to swell beautifully throughout the year, rising in size and shape, putting it on in different places, each body accommodating the changes in their own ways.

These teachers also show me the rhythm of the slow decrescendo post-birth; bodies taking three, six, nine months to gradually come back to a form of strength and shape that is similar, but not necessarily exactly the same, as before. The plump middle is a gorgeous time of ripening, exactly as it’s meant to be.

What I was surprised to discover, is that the maternal storage tissue is not just for the pregnancy: it is our way to provide food for the baby after it’s born.

It’s not just the pregnancy part of childbirth that needs you to add weight to your body. It’s the need to provide food and fuel for a rapidly growing human that causes our bodies to pack on pounds like we’re about to hibernate for a year. We are the primary food and fuel resource for a brand-new infant, and we need to be prepared accordingly.

Why is a baby born at nine months? By most accounts, humans are born “too early,” to survive outside of the womb. Conventional wisdom (and science) holds that if babies stuck around inside for longer, they would get too big, and we wouldn’t be able to get them out through the narrow hips and size of the birth canal.

Yet more recent scientific theories speculate that the 9-month gestation period for human babies is cut short at nine months not because of the size of the head and the brain, but because of the metabolic needs of the fetus and the mother.

This theory suggests that hip width might not be the limiting factor. We might be giving birth to babies at this early stage because if the fetus stayed in the mother any longer, the mother would no longer be able to provide food/energy at a fast enough rate. That is, the metabolic function of the mom’s body reaches a peak point where she can no longer digest and provide enough nutrients for both her body and the fetus.

(Anecdotally, I know that I am already constantly hungry, and eat all the time. I wake up and eat in the middle of the night, I eat constantly throughout the day, and I still feel a sense of hunger even when I would normally be very full.)

Beyond the anecdote, however, this made me realize that much of the job of the mom in the first 3 months of an infant’s life (and really, the first 6 to 9 months, or whenever they start eating solid foods on their own) is to provide an unlimited source of fuel and energy for their offspring.

Unlimited source of fuel for a baby that’s going to grow rapidly.

Hence the packing on of pounds earlier on in pregnancy, before the baby gets bigger.

Maternal storage tissue.

It all makes sense.

(I got your back, kid.)