The fourth trimester is that tricky period of time that you never seem to forget and can never truly remember, either. It's all kind of a blur. It's probably from all the hormones, lack of sleep, and proper nutrition. Those first days and months you spend as a new mom are so fraught with worry, coffee, and poop, who could have perfect recall of such a time? And yet, when you see others go through it, your whole body gives an involuntary shudder like someone's just walked on your grave. When does the fourth trimester end? Because when you're in it, it seems to stretch out to infinity.
Technically, the fourth trimester is the period of time from birth up until the end of your baby's third month, noted Midwifery Today. The reason it's referred to as the "fourth trimester" is because of all of the growing and developing your child continues to complete after they're born. You see, most mammals are born with a higher ability to function outside of the womb than human children. Heck, even panda babies — born naked, blind, and the size of a stick of butter (lucky panda mom) — have control over the muscles in their head and neck. Human babies can eat, breath, eliminate waste, and cry at birth. The fourth trimester is the period of time they learn to recognize people, track with their gaze, hold their head on their shoulders, and entertain themselves by gnawing on their own appendages.
By all basic measures of evolution, your baby should still be tucked inside your womb until it can come out and at least keep its head from lolling on its shoulders Weekend At Bernie's style. Alas, evolution stopped our hips from growing so wide as to accommodate a 14-pound newborn with a head the size of a cantaloupe, so here we are, trying to figure out how to cope with a teacup sized human with lungs that put out all the sound of Drake concert while you're still hormonal AF and you can't sleep. Also, you're probably wearing an adult diaper and your boobs are leaking more than the White House.
The Family Medical Leave Act Commission (FMLA), took the fourth trimester necessities into account when developing the plan that allows mothers to take off a full 12 weeks after your baby is born. The idea was to keep mothers and babies together while the mother recuperates and the baby continues its development. While I feel that 12 weeks can be woefully inadequate, and it's criminal that we don't pay our mothers for their maternity leave, this is the system we have, and for now, we must work within its confines, however extraordinarily difficult it may be.
So, when does the fourth trimester end in truth? For me, even though I was told it ended when my child was 12 weeks old, it didn't feel truly over until after my daughter overcame her 4-month sleep regression. Because at that point, she'd been sleeping for six or seven hour stretches, and then at 14 weeks? She was back to waking every two hours. This lasted about two weeks and it was miserable. For the most part, during the day, she was happy as a clam as long as she was on me or near me, but at night she was another creature entirely.
Not to mention the fact that I was still a breastfeeding machine up until about 16 weeks postpartum. I think that while babies do a lot of growing in the first 12 weeks, the first 16 is what I commonly think of as "the fourth trimester." There are ways to cope with this trimester, like the heavy use of baby carriers and a practical intravenous drip of coffee, but truly, the first 12 weeks after having a baby are about reframing your expectations and just trying to keep your head above water while you stare down at this amazing thing you've created. Don't worry, you'll barely remember the sleep deprivation, but you'll always remember the first smile.
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