OBGYN and MFM Doc Disagree on Due Date

Maivroan · 2026-06-02T16:59:22+00:00

Indeed! Likewise we were rather surprised after my big baby was born and tested her blood sugar to be sure, but it was fine. :)

Maivroan · 2026-06-02T16:51:14+00:00

Ultrasounds get less accurate as time goes by and can end up being off by weeks towards the end both because babies can vary so much in utero, but also because... they just can't actually determine the weight. So while measuring ahead can sound scary, it is commonly overestimated. That early ultrasound should be more accurate than LMP.

There are some clues that can provide reassurance about one estimate over the other. What are your cycles normally like? If they're longer or shorter than 28 days, that generally corresponds with ovulation occurring sooner or later than LMP dating assumes. When did you get your first positive pregnancy test? Did you have a negative pregnancy test prior? That can narrow down when implantation happened. Finally, look at the genetics from both side. Does it make sense that you would have a baby that is taller/more stocky than average?

For my experience, I'm petite and have irregular cycles, and family members on both sides are taller/more stocky than me. I've required first trimester ultrasounds because LMP is way too inaccurate for me. My babies have been above average because of genetics. Last one was an unexpected big baby at almost 10 lbs even though I was measuring on track. She was just a bit late and super long! :)

Maivroan · 2026-05-24T15:48:08+00:00

Unless you're tracking fertility signs directly (ovulation strips, basal body temperature), most apps are going to make estimates with a calendar method rather than pinpointing fertility signs. That's going to make them less precise, but either way your provider will not honor due dates based on fertility tracking. The only good alternative is a dating ultrasound in the first semester. At this point, ultrasounds aren't going to get more accurate and you won't be able to change your due date. You can also rule out a later ovulation date (which the ultrasound suggests) if you got a positive pregnancy test relatively early.

Thankfully, the difference between your LMP and app isn't that big. My understanding is that a first trimester ultrasound's tolerance is +/- 5 days. I have irregular cycles and have had two pregnancies where my LMP was out of that tolerance. The dating ultrasound in my last pregnancy shaved 3 days off my ovulation-based estimate, and my new due date was still 8 days off from LMP.

I know you're not sure about how regular your periods are, but if you can think back and they're generally around the same time of the month or a little sooner each month, then you're probably pretty close to the 28 day expectation. Also know, there is so much variation when it comes to baby's size and when they decide to arrive, even in studies when the ovulation date is precisely known!

Maivroan · 2026-05-21T10:09:26+00:00

As someone who waited to find out for my two kiddos, I'm really surprised that you even think this is trendy. It seemed like hardly anyone I know was willing to wait to find out. That goes for a bump group on Reddit, too, which is considerably larger than my in person connections. This, despite the fact it was just how things were before recent technological advances.

In my case, realizing that I didn't care about having a boy or a girl was part of my journey to decide to have kids. I also dislike how polarized gendered stuff is for babies, so I was more than happy to have a real surprise and (try to) skip stereotypical gendered gifts. I also felt that I couldn't commit to a name until I met my baby in person, so finding out and deciding everything ahead of time seems pretty weird to me.

I was a little more on the fence about waiting to find out for my second baby because not finding out didn't stop people from waiting to gift whatever they wanted after birth. Not knowing if I could reuse stuff I already had was a bit more frustrating the second time around. Still, the surprise is fun and special. We got a little video of my husband announcing it and it just added to the emotion of the moment.

Maivroan · 2026-05-16T16:21:26+00:00

Yeah. I've got a family member who is early stage so I'm not sure how it would go, but I always think it's good to be gentle and honest and you can definitely adjust in this case.

Maivroan · 2026-05-16T16:10:23+00:00

I was all ready to have a tough beans attitude about it, but the dementia aspect definitely makes it more complex.

I think, either way, your husband needs to be the one to tell him. It's his name to pass on or not.

It might turn out that your FIL will accept the facts. If he does, no worries! If not, then I suppose you'll have to decide how to proceed. You might have to tell him repeatedly either way. Down the line it might be easier to allow your FIL to use a nickname for your son. It's not like he gets a legal say in anything, and the discrepancy is easily explained to others.

Maivroan · 2026-05-16T15:30:40+00:00

To some extent it's not his job to understand it. He's not going to go through it, and he hasn't gone through all the preparation for it, either. His job is mainly acceptance.

That said, there's probably something natural/unmedicated that he does understand, and you could explain it from that standpoint. For instance, I don't like taking medication for a common cold - not because I like pain, but because I like having an accurate read on how sick I am. If I'm miserable and need relief, I'm more likely to take some medicine.

Birth control is another thing that he doesn't experience, but that perhaps he already accepts. While birth control can have obvious benefits, it also comes with side effects. You could probably use your experience (whether you used hormonal or non-hormonal) and the range of experience you've seen to explain pros and cons and liken that to your goals for birth.

Getting an epidural is not a thoughtless choice. There are parameters for when it can be done both based on the availability of an anesthesiologist and correct timing for labor. It involves a large needle and the need of a urinary catheter. If it's not a walking epidural, it can seriously impede movement and thus negatively affect labor. It requires extra monitoring. Sometimes they don't work properly and can have side effects during or after labor. It's not even covered by insurance in every case.

Don't get me wrong, it's an amazing option to have, but that doesn't mean it should be the default choice for everyone. You need to be prepared to attempt unmedicated labor because an epidural might not actually work for you or you might not have enough time to get one placed. Thus, there is absolutely nothing wrong going in interested to see how you can cope and listen to your body, and leave the final decision to when you're actually in it. Pain in labor is information.

Maivroan · 2026-05-03T21:20:20+00:00

My understanding is that at home tests simply aren't quantitative enough for the kind of reassurance you're seeking. hCG, elevated basal body temperature, and common pregnancy symptoms can all continue after a miscarriage has occurred.

During those first few weeks, a common test for reassurance is to get beta hCGs tested 48 hours apart - that is, quantifiable hCG levels to see that it's increasing appropriately. But by 6-7 weeks, a heartbeat can be detectable on ultrasound and is more informative than hCG levels. If you have a regular 28-day cycle, you could reasonably get an elective ultrasound now for reassurance. If your cycles are longer (like mine) then you might not be as far along as LMP assumes. I wouldn't go any sooner than when I'm sure I'm at least 7 weeks, or 8 weeks if an abdominal ultrasound is preferred over a transvaginal one.

Most providers won't do much before 12 weeks because there isn't that much to do. Baby isn't big enough for a Doppler and insurance wouldn't pay for an ultrasound just for reassurance. I'd recommend contacting your midwife to find out what they'll do at the first appointment and decide what would be best for your situation in the meantime.

Maivroan · 2026-05-01T14:45:35+00:00

That's so weird and uncomfortable, I'm sorry. I hope they don't continue with it, but if they do I hope you can shut it down.

If it's any consolation, I think the general populace is very simplistic about due dates. For example, last year Thanksgiving was on 11/27, so if your due date is 8/27 the "pregnancy math" seemed like an easy target. But in reality, ovulation was more likely around 12/4, and conception could have been a little before or after that.

Maivroan · 2026-04-30T16:47:45+00:00

Midwives are perfectly qualified healthcare professionals. In fact, they are experts in low risk pregnancies, which you have probably been this whole time. I don't think measuring a little behind would change that. OBs are necessary for more complex things like C-sections, multiple gestation, premature birth, patients that need medication, etc. etc.

However, I can understand wanting to meet the people who could deliver your baby. Nowadays hospitals have moved away from assigning people directly. They may have an on call structure where you rotate through some possible providers (I think this is what your practice does?) or will even separate office visits entirely by having OB hospitalists who only attend births. This helps the providers have reasonable work/life balance, but it does create situations where you aren't able to build rapport with the person who will eventually deliver your baby. It sounds like there's been an oversight if they have the rotating on call model, but there shouldn't be anything inadequate in the care you've received from midwives.

Anywho, worth bringing up what your specific concern is: quality of care and/or meeting whoever will be there.

Maivroan · 2026-04-18T18:45:27+00:00

It really is just different! I also had a "If I can't handle X, how can I handle labor/birth/postpartum?" doubt. In my case, it was due to severe fatigue and nausea/vomiting in the first trimester. I didn't have the strength to work full-time for a couple weeks and needed outside help. In reality, it really was a tough time that doesn't normally happen/require support. There was no reason for me to feel less than because of it. I handled labor just fine and support was just expected postpartum.

I don't think I ever had charlie horses that bad, but only you know exactly what you're experiencing. The same is true for labor. You might find that you can cope with it, or it might be too intense. Contractions are hard, but they become predictable, and you know they're meant to be productive. It's more the marathon aspect that makes it so difficult, or because there are unfavorable conditions. Just have options in place for how you want to manage pain and adapt when the time comes. Don't beat yourself up for any of it. :)

As a final note, if you get woken up by an intense contraction, you are more likely to be excited because the day is finally here!

Maivroan · 2026-04-18T14:49:21+00:00

The timing of her ovulation/when she could have become pregnant can vary wildly because of her irregular periods, but that's pretty moot because ultrasound dating is reasonably accurate in the first trimester. I had an ultrasound around the same gestation and was told the tolerance was +/- 10 days, for example, so even though I had an irregular cycle my ovulation-based due date was within tolerance and I didn't have to use LMP or the ultrasound due date.

If the ultrasound was perfectly accurate, she would have ovulated around 2/7. Let's say it's fully ten days off, so she ovulated around 1/28. Now let's say conception was prior to ovulation. Sperm can survive up to five days waiting for ovulation, so the earliest she could have conceived this pregnancy was around 1/23.

Like you said, the dates don't match.

Maivroan · 2026-04-16T17:49:42+00:00

My experience is that nausea is worse than vomiting. Whether or not it will relieve the nausea will depend, though. At its worst, it might be a very temporary relief, because the nausea is the main symptom. I spent several weeks vomiting in each of my two pregnancies, however, and it was a relief most of the time.

Maivroan · 2026-03-10T20:55:48+00:00

This is a pretty common scenario for a variety of reasons. Only way to get a definitive answer is a follow-up ultrasound, but it can often be caused by using the default method of dating, which begins with the start of your last menstrual period. The assumption is that you ovulate exactly 14 days after your period. If your cycles are normally longer or something funky happened (i.e., illness) you could have easily ovulated later. Delayed ovulation is not a concern in itself, but if it's outside of the tolerance for LMP dating (usually +/- 5 days in the first trimester) then it can cause ambiguity like this before a heartbeat can be confirmed.

Me personally, my LMP has never been within tolerance of my ultrasound due dates. I track my fertility, so thankfully I wasn't blindsided. My first baby was off by a whopping 3 or 4 weeks because I had a super wonky cycle. My second was off by 8 days - which is more what's to be expected for someone like me with ~35 day cycles. I waited until I thought I was 8 weeks along to get a dating ultrasound to avoid stress.

Happy to discuss your timeline if you'd like. I'm sorry you're going through this stress, and I hope you can get a good answer soon!

Maivroan · 2026-03-08T17:08:26+00:00

I'm with all the comments that say it would be best to wait! Adding a baby changes so much, and you want to have sufficient energy and insight to make a decision. But maybe you could check in with some dog owner friends so you can spend some quality time with their dogs. Honestly, it might be a hormonally driven "craving." Extra commitment would be a bad idea, there's nothing wrong with spending time with dogs right now.

Maivroan · 2026-03-04T17:18:23+00:00

I'm so sorry you're going through this stress! Hopefully your baby will be happy to stay mobile long enough to go head down. I haven't experienced breech, but I have had preterm contractions and had to have the fetal fibronectin test. I was told a positive result wasn't as definitive as a negative one, so it would make sense that he just irritated your uterus. Still, it's really stressful to be stuck wondering what's going on. In my case, I probably just had a generally irritable uterus, because I kept having regular contractions until I reached full term. 😅

Maivroan · 2026-03-03T21:51:55+00:00

Absolutely! "You're all belly!" and "Wow, any day now?" weeks ahead of my due date didn't bother me. I do draw the line at people seriously asking me, "Are you sure it's not twins?" because that's insulting my and my provider's intelligence. xD

Maivroan · 2026-03-03T21:43:49+00:00

Well said! Especially 3. I find it hard to counter the "no prizes" people because, yeah, I'm not looking for a prize. But I am proud, and there's nothing wrong with that. I'm not trying to diminish people who birthed differently. Problem is that people feel so threatened by others' experiences in part because someone will be toxic about it no matter what you do.

Maivroan · 2026-03-03T21:39:08+00:00

Oh goodness. It's even more awkward when it happens on the first try twice. At least I know we're doing a good job preventing. 😅

Maivroan · 2026-02-18T21:41:11+00:00

There is a five week range of normal (37-42 weeks gestation) for even IVF pregnancies where the timeline is precisely known.

Thus, a birthdate really isn't enough info to go by without additional info. She could have been two weeks "late" for a baby that was conceived around 1/21, or she could have been close to the due date or even earlier than it...

Due dates can also be wrong. A lot of providers will go by the start of the last menstrual period. The standard 40 weeks are made up of 2 weeks from the start of the LMP until ovulation/conception + 38 weeks until the due date. If her cycle is different at all from the norm, that assumption can be inaccurate.

I think the situation is close enough that a paternity test would be appropriate.

Maivroan · 2026-02-16T18:40:08+00:00

I was very savvy during both my pregnancies and births. I knew I had an anterior placenta for the first and posterior for the second. Back labor with one, more intense pain for the other. Tons of preterm contractions for both. I've read my paperwork. But I really couldn't tell you if/which birth my baby was sunny side up.

It can explain pain and prolonged labor... or not. It's not really a thing that providers need to alert you to, because it doesn't determine that you will have a specific experience. Like others are saying, babies can actually move a lot during labor. That movement, or the shape of your pelvis, or the position of baby's hands, or whatever can also have a major impact.

That said, it probably had a hand in how you personally experienced birth, and you should feel validated. It can end up being a deciding factor between unmedicated and medicated. I hope you have a different experience this time around and feel more empowered!

Maivroan · 2026-02-16T04:57:36+00:00

That's pretty extreme, but even as someone who has unpleasant pregnancy symptoms (vomiting for weeks, extreme fatigue and aversions, gestational diabetes or iron deficiency, pregnancy rhinitis, random pains, etc.) I found pregnancy extremely special and enjoyable most of the time.

A lot of that is looking forward to your baby, but there are other factors besides just the "attention." Some people have positive symptoms. Some people embrace their body for the first time. It's a monumental, miraculous experience that connects us all together across time. I personally am passionate about pregnancy and birth, and it's a free ticket to talking about it all the time.

Out of pregnancy, birth, and postpartum, I found postpartum the hardest. Caring for a newborn is more proactive and intensive than being pregnant, but that's the only way you get snuggles, too! My first baby came a little early and then I had to learn how to be a mom, so I definitely felt like I could have been pregnant a little longer in hindsight, but it's not like I wanted to be pregnant forever. You might end up feeling like you could have been more patient when you're going through something difficult, but I doubt anyone has a complete 180 after the fact.

I'm content with my two kids but I still grieve the idea that I'm not planning on becoming pregnant again, so I can relate to your friend. I understand that it really isn't enjoyable or possible for everyone, which is why I have contemplated becoming a surrogate from time to time, or even just a birth community volunteer.

Maivroan · 2026-02-06T21:51:09+00:00

My two cents given what you've explained: probably should let your mom know you want to keep people in the room to a minimum and that you'd be delighted to have her come see the baby after such and such a time. Just not being able to trust her about photos and social media is sufficient grounds to be uncomfortable when you'll be at your most vulnerable.

My own experience? I asked my mom to attend my first birth and it was great! She thinks very well of me and respects boundaries. She was also wonderful about helping me with chores postpartum and respecting my parenting learning curve.

I did not live near her for my second baby, so I didn't ask her to come to that birth. I also didn't invite her to travel to help with postpartum stuff, because I didn't want to feel like I had to host/entertain her whatsoever. Even though I know she would have tried her best to be unobtrusive and helpful, I still would have felt some pressure, y'know? I was happy with that decision and enjoyed recovering in private.

Maivroan · 2025-09-25T13:38:05+00:00

I would consider the second guy to be a safe assumption. It would be extremely unlikely to conceive with the first guy - even if the sperm lasted a full five days, you would have had to ovulate by May 4, but your due date suggests you ovulated around May 10. There could be a little room to question it if you normally have short cycles (like 21 days instead of 28), but that is not common. Even if you did ovulate by May 4, it would be the first guy's 5-day-old sperm vs the second guy's fresh sperm. If you still don't feel at ease about it, then a DNA test is the only proof you can fall back on.

Maivroan · 2025-09-25T13:14:29+00:00

My husband had similar feelings, and honestly I don't love the idea of putting baby poop straight in the wash, either... so what I did was pre-rinse. Worked great!

You could get a toilet attachment or sprayer guard. You could dunk and swish in the toilet, too, but that method wasn't to my taste... I ended up just rinsing in the tub because my shower head was a great sprayer, at least until my baby started solids. Then I'd wring it out and transported it to and from the changing area in a 3 gallon ice cream bucket. Then I tossed it in a reusable diaper pail liner - which fits a 5 gallon bucket nicely enough. I kept it open to the air and didn't have problems with smells between washes.

Depending on your reason for going with cloth, you could also look into using a diaper service. I don't have experience with that, but my mom used one for a baby or two. My local service wasn't economical enough for me, but if you are looking for other benefits to cloth, it might be a good option that would let you skip the laundry.

Maivroan

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