Babies are built like houses. You have to start at the foundation and go in a certain order. You can't put up walls if you don't have your foundation laid. You can't put on a roof if you have no walls. See what I mean?
Growing a baby and a placenta are like this...the same steps have to occur in the same order in all pregnancies. Because of this, ultrasound can give us an idea of how pregnant you are.
An ultrasound done in the first trimester has a margin of error of about plus or minus (+/-) 5 days -- which means somewhere in a 10 day span is your due date. So if they say you are due September 15, that could be 5 days either way (10th to the 20th). Remember: just like all the tomatoes on your plant aren't ready at the same time, babies come early and babies come late. But we know the date given in the 1st trimester is the most accurate because the business of building a baby is done in the same order, and the construction looks about the same across the board, so we expect to see similar timelines for everyone at this point.
In the early part of the second trimester, the margin or error is about +/- 8 days. This means that September 15th date is now widened to September 7th to September 23rd...again, accounting for variation in baby-readiness.
But, just like rain or lack of supplies can make building a house take longer, or a sudden addition of extra workers can make building a house go faster -- the third trimester is where we see this happen. This is why the third trimester is the least accurate when it comes to dating the fetus by ultrasound.
The margin of error in the 3rd trimester is about +/-22 days! This means that September 15th date now expands to August 24th to October 7th! This is why, if a care provider changes a due date in the 3rd trimester, we should really ask what evidence is being used to make that decision.
The third trimester is where we see genetics come into play. If you are tall, your baby may measure big because their leg bone is long, like yours. If your partner has a big head, your baby may be estimated older because their head measures bigger than most of their unborn peers. The variations in physical traits are like the roof coming on sooner, or later, and the actual age of the baby getting lost in the ways we measure babies (head circumference, abdominal circumference, arm bone, leg bone, etc.).
So, all of that to say, in the first trimester you have the closest, most accurate dating of how pregnant you are.
Read more about Pregnancy Dating...
I must preface this by stating, it is not an uplifting tale of birth. I know in our culture we hear more birth horror stories, and it is not my intention to perpetuate that. This is the beginning of my birth experiences, and although I take credit for my missteps, I hope 1-it can serve to help get you thinking about your birth options, and 2-you will read my other experiences of birth to see the evolution which came through my personal education and faith.
When I was pregnant for the first time, I fit the typical American mom-to-be stereotype. My older sister was three months behind me pregnant with her first, and she was planning a homebirth with a midwife. Not me, I wanted a hospital birth, and the cherry on top was, I chose a female obstetrician just knowing she would "get me."
My appointments were a lot of waiting, waiting, waiting for her to show up, and then her rushing me out in important-doctor fashion. One time I was made to wait so long, naked bottom on the papered-table (in a very hot, windowless room) that I sweated through the paper -- how terrible was that? But I was a good girl, and I did as I was told. "Take off your pants and sit here, she will be here soon." How humiliating. (Please, if it is not too late for you, keep your pants on until you practitioner arrives, and just sit in the chair while you wait -- it's allowed!).
I am not sure if you know this or not. With your first pregnancy it may come as a surprise -- with subsequent pregnancies it is an easy thing to forget until it creeps up on you, but it gets terribly uncomfortable growing a baby who sits on top of your bladder and underneath your rib cage. I have long told my childbirth classes this, and as of late, I am reminded again of its truth.
Being 33 weeks pregnant, I have my list of complaints. I feel like this baby can't come fast enough. I even imagine going into labor early -- like today early -- just to be done with it.
My back and hips are aching like never before (surely a sign my body is feeling too old to be going through a pregnancy again, right?). Sleep is something that comes in fits and pieces. I feel bad for my husband as I toss, turn, try to roll over but feel more like Ralphie's brother in "A Christmas Story," lying on the ground in his snowsuit saying, "I can't get up!" Add to that restless legs that shake and quake of their own volition, the 5 pillows I have behind, around, under and between various body parts, and the snoring (yes, the snoring!) that wakes me -- the snorer! -- and I imagine there's nothing peaceful in our bedroom right now.
My baby is still high enough that I can relate to this scene from "Tommy Boy," just replace bear claws with baby butt:
It is surprising how hard a baby butt can actually be -- but there is not a lot of fat there, and it becomes this firm blockage that prevents me from bending over to put on socks or tie my shoes or reach down to release the emergency brake on the car -- and it is just plain uncomfortable.
Even with the baby still not having "dropped," my poor bladder is being pushed to its own limits. I am convinced I am currently the top toilet-paper-user in the house, visiting the bathroom 4-5 times a night, and so many times during the day I probably use a roll every 24-hours. I have adopted a policy of mandatory-usage if I get within 12 feet of a bathroom. My logic is, even if I don't have to go right now, I will in 10 minutes, so I just pre-emptive-strike it.
I notice I make a lot more noises as I progress through the normal tasks of the day. I sigh and groan and yelp as I shift from sitting to standing, getting in and out of the car, bending down to (attempt) tying my shoes. I swear I am not doing it on purpose, these sounds just escape my lips before my brain can even say, "That was quite the old-lady-carrying-the-cat-food-bag-into-the-house noise." No offense to old ladies who have to carry the cat food bag into the house and may make noises while doing so.
This baby gets the hiccups probably 6-8 times a day. I can't figure a pattern -- sometimes it seems like they may come after I eat, other times they come when I am hungry. Sometimes they just come. They aren't the worst things in the world, they just feel like lttle spasms that jolt my uterus in various places every two seconds. They can space out longer or shorter, but in my scientific explorations, I have noted they most frequently come every two seconds.
These are just the things that bother me the most. There are more issues I can mostly overlook. With this list of complaints, though, it isn't hard to see why so many women press for inductions or agree to inductions when offered. It is hard to wait! It is uncomfortable to wait! It pretty much sucks! Don't believe that rare woman who, at 38 weeks pregnant says, "I still feel great, I am in no hurry to be done," because while she does exist, she is generally the exception, not the rule.
The way we look at due dates, we often feel "overdue" by the time that day rolls around. We are conditioned to believe our (bad, uncooperative, lazy) babies are just kicking back in there, buffing their ever-growing nails on the inside of our uteri, taking up time and space, while we grow more and more uncomfortable.
When I was pregnant with my first baby, I read in "What to Expect When You're Expecting," that doctors only induce if it is medically necessary; so when my doctor offered, on my due date, to induce me, I took her words as medical advice being as they came from my medical practitioner's mouth. Maybe my first clue should have been the way she asked without giving any scientifc rationale: "Are you ready to get this over with?" Well, heck yeah, I was ready to get this over with! That's a vulnerable place to be! Miserable, anxious, wanting that baby out from under your ribs and into your arms. Who would say no? And with that one question, I was set up to believe my body was done doing anything important for my baby and wouldn't go into labor on its own.
I am not a patient person. I hate waiting for things. It took every ounce of confidence and trust I could muster, and some I didn't even know I had, to wait on my babies and pregnancies the next two times around. But the evidence shows birth is safer for mom and baby when they are allowed to work together -- like Mario and Luigi saving the princess in tandem -- to let labor begin on its own.
Many expectant parents find the last weeks before their baby’s arrival to be fraught with a rainbow of emotions. The excitement builds as the due-date comes. This date has been the goal. Although realistically only 5% of babies are born on their due dates, we still cling to that date as if it means something bigger than it does. Just as every fruit on the same tree reaches ripened maturity at different points in time, so do our babies. One survey suggests 7 out of 10 babies are born past their estimated due dates (as a birth doula, I can say this backs-up my experiences with mothers and babies).
♥ four young boys and a boy dog (offspring)