Could my due date be wrong? 01/11/2009?

If my last period was on 04/07/2008 wouldn't that mean I would be pregnant for 10 months if my due date is 01/11/2009? On my last visit my uterus is measuring 1 week ahead of schedule. Does that mean I could have my baby earlier than anticipated. Is is possible for me to have her in December? I'm just curious. This pregnancy is going by so fast that it's scary.

The gestations cycle works out to be about 9 1/2 months. But, baby is going to come when baby wants to! I was a week late with my first, and right on time with the 2nd.

While on this topic, I have a question I have never understood.

A normal pregnancy lasts 40 weeks.  A normal pregnancy, also, lasts 9 months.  So isnt't 40 weeks 10 months?  Or 9 mos really 36 weeks?

Or maybe as mom6 says above its really 9 1/2 mos or 38weeks??

Well,  40 weeks is about 280 days, which roughly works out to 9 1/2 months. Most doctors will give you a due date of +/- 14 days (2 weeks) because some babies go longer.

I always calculated by weeks as in 40 weeks.  Months doesnt work right.

Original Post by spuckine1:

I always calculated by weeks as in 40 weeks.  Months doesnt work right.

 Ditto. You'll only confuse yourself counting in months.

Also don't forget that most first babies come at 41 weeks 3 days!  The timing will really depend on when the egg implanted and started to multiply which could have taken up to 3 or 4 days after ya know.

Ya I always looked at it like this. Your usually a month pregnant by the time you figure out your pregnant. Or something like that. I know its really confusing. HAHA. My last boy (who is now two years old) I had the same conversation with my doctor. I couldn't comprehend my due date. But technically women are pregnant 9 1.2- to 10 months but we've always just said 9 months I guess. My due date was right on with my last boy. Well...not exactly right on he wanted to stay in there. Liked it I guess....was 10 days over due. OMG I was so tired of being pregnant. But that's another topic!

10 months is based on gestational age I believe and the 9 month deal is from conception. I think this is the period from which the egg is released to the time it is fertilized. Since 2 weeks after your period, you are most fertile, that is where the extra time comes into play.

Usually, a guess based on you period could be off up to 2 weeks. It depends on the length of your menstrual cycle. If you knew the exact date of conception, that would be pretty accurate. As far as the fundal measurements go, it has a lot to do with the baby's positioning and your size. It can also be off either way by several weeks.

You will know the closer it gets just how close, but it's still a surprise. LOL! I am going to be delivering a week and a half early. LOL!

yes 40 weeks is 10 months..... but a full term pregnancy is considered anywhere from 36-40 weeks........

The 40 weeks is from the first day of your last menstrual period- ovulation usually occurs about day 14.  Full term is anywhere from 38 to 42 weeks!  Tape measure measurements of fundal height (top of the uterus) are an estimate but help your careproviders know that over time, your uterus is growing appropriately.  Guess you could possibly get that tax deduction in for "08! Best wishes!

Hi,

I'm a midwife. Maybe I can help answer this question. It is confusing.

Unfortunately, most calculations for pregnancy today are still based on Naegle's Rule which is archaic. Naegle lived in the 1700's and was the first doctor asked the question, "How long is human gestation?" He figured it up to be 10 lunar months from the first day of the last menstrual period which is pretty close but his answer was never and has never been based on research.

10 lunar months is 40 weeks because a lunar month is exactly 4 weeks. Our modern calendar is not a lunar calendar. Our months have anywhere from 28 days to 31 days and in 9 months those extra days really add up. So when you hear "9 months" it's referring to the modern calendar and not the lunar calendar which is how pregnancy is really dated. Medically all pregnancies are counted in weeks, not months.

Now back to Naegle's rule. All this time and even though it has been proven to be inaccurate in dating normal pregnancy, Naegle's is still used by most practitioners today. But Naegle's is not the best way to date a pregnancy accurately.

Early sonograms are more accurate but even some sonogram programs are based on Naegle's Rule.  Fortunately, there is a method for dating by last menstrual period that is more accurate because it is based on controlled studies of normal human gestation. In other words, how long is normal pregnancy if we don't interfere with inductions? This method is called the Wood's method of calculation. 

Wood's also takes into consideration the woman's normal cycle length because that makes a big difference. You see most women ovulate about 14 days BEFORE their next period starts. But not all women have a 28 day cycle. So if a woman has a 30 day cycle, you need to add 2 days to your calculations. If she has a 26 day cycle, you subtract 2 days. If her cycle is irregular or unknown, you really should date the pregnancy with a sonogram and not rely on either Wood's or Naegle's.

Anyway, based on a 28 day cycle, normal gestation for a first pregnancy is 41 weeks and 3 days (from the first day of last menstrual period + or - the difference in a 28 day cycle). .And normal gestation for any other pregnancy is 40 weeks and 5 days (from the first day of last menstrual period + or - the difference in a 28 day cycle).

And remember it's all just an average. Babies can be born without problems anywhere from 2 weeks before a "due date" to 2 weeks after a "due date." What's important is to get good prenatal care from someone who monitors the baby's well being closely at the end of the pregnancy but also doesn't rush the pregnancy just because some calculation says you are "due" or because of impatience. While post dates can be a problem, it is also true that too many babies in the US are being induced way before they are fully mature just for convenience.

No one likes waiting out the last few weeks of a pregnancy. Those are very hard times for pregnant women. But they are also vital times for the baby's development. During the final weeks of pregnancy the baby is maturing his or her lungs and is gaining valuable brown fat to help him survive trauma or illness if necessary. Also labors that occur normally give the baby the benefit of hormones which make his journey much less traumatic for him. So pregnancies should be monitored closely but never rushed unless it is really medically necessary.

~ Beth

I had to have an induction with my first because the doctor feared he would be too big for my birth canal. He didn't want to have to do a c-section, so he induced me about 10 days after my "due date"

The second baby went into labor naturally. Was about 5 cm when I went to the hosp!

Well done Beth, a great explanation.  I remember when I was a student midwife sitting in class trying to figure out the 9 month, 40 week dilemma.  I actually wrote out a chart so I could figure out when someone said that they were 5 months, how many weeks they were.  Its like pounds and ounces.  I don't know about America, but here we have measured babies in kg since before I was born, but everyone still wants to know how much they weigh in pounds and ounces, and how long they are in inches!  I once had a student who refused to work in kg until I asked them to quickly calculate what 10% of the birth weight of a 8lb 2oz baby was to see if its weight loss was within normal limits.  They soon came around to metric.

Anyway, that's boring Midwife stuff to anyone but us.

What drew my attention to this post was a due date of 1/11/09, which to me would be impossible, and therefore a serious miscalculation. Then I realised that it was using the US method of stating the date.  In Australia, we state day/month/year, which seems to make most sense going from smallest to biggest. So I read it as the 1st of November 2009, not as 11th of January, lol! Imagine being pregnant for over a year!

I have no help on the medical side of due date figures. I have never had my babies come anywhere near when they were "supposed" to. My first was induced supposedly a week before my due date, and ended up having all the signs point to her being 4-5 weeks early. Then with my second, they said he was early, but my water broke on it's own, so they let the labor happen, and he was almost too big...the next three were pretty close, if you use the rule of thumb that you need to give/take 14 days for your due date. And no matter what, pregnancy takes forever.seriously. I always start my pregnancies with a bang, and by the end, when anyone asks how I am doing, I just tell them I am waiting. When they ask what for, I tell them for this to be over (the pregnancy). I must say, however, that my last little guy came 6 weeks early, and though I thought he was on time, this time the doctor was right. We had a rough go of it for a while... Either way, Good luck! Labor won't start til your body's ready, so pay attention to it!