Generally, an overdue baby will be induced once it is two weeks past its expected date. Some of the methods of induction include:. This page has been produced in consultation with and approved by:. In Victoria, you can have two types of abortion: surgical and medication. Both types are safe and reliable. You can have a medication abortion up to nine weeks of pregnancy.
You can have a surgical abortion from around six weeks of pregnancy onwards. Pregnant women with asthma need to continue to take their asthma medication as it is important to the health of both mother and baby that the mother's asthma is well managed.
Even if your baby furniture meets every safety standard and recommendation, your child still needs close supervision. The cause of birth defects is often unknown, speak to your GP if you are at increased risk of having a baby with a congenital anomaly.
Melissa shares her story of how her baby caught chickenpox at 5 weeks old. Content on this website is provided for information purposes only. Information about a therapy, service, product or treatment does not in any way endorse or support such therapy, service, product or treatment and is not intended to replace advice from your doctor or other registered health professional.
The information and materials contained on this website are not intended to constitute a comprehensive guide concerning all aspects of the therapy, product or treatment described on the website. All users are urged to always seek advice from a registered health care professional for diagnosis and answers to their medical questions and to ascertain whether the particular therapy, service, product or treatment described on the website is suitable in their circumstances.
The State of Victoria and the Department of Health shall not bear any liability for reliance by any user on the materials contained on this website. Skip to main content. Healthy pregnancy. Home Healthy pregnancy. Baby due date. Actions for this page Listen Print. Summary Read the full fact sheet. This educational content is not medical or diagnostic advice. Use of this site is subject to our terms of use and privacy policy.
Registry Builder New. Due Date Calculator When is your baby due? Use this pregnancy calculator to find your due date based on the date of your last menstrual period, conception date, IVF 3-day or 5-day transfer date or date of your last ultrasound. Calculation Method. The first day of your last period. Date of Conception. Date of Transfer. Date of Ultrasound. Medically Reviewed by Aaron Styer, M. Medical Review Policy All What to Expect content that addresses health or safety is medically reviewed by a team of vetted health professionals.
How to Calculate Your Due Date. First day of last period Most pregnancies last around 40 weeks or 38 weeks from conception , so typically the best way to estimate your due date is to count 40 weeks, or days, from the first day of your last menstrual period LMP. Conception date Calculating your due date based on the first day of your last period works well for women who have a relatively regular menstrual cycle.
Soon after, ultrasound measurement replaced last menstrual period LMP as the most reliable way to define gestational age Morken et al. A large body of evidence shows that ultrasounds done in early pregnancy are more accurate than using LMP to date a pregnancy. In a Cochrane review, researchers combined the results from 11 randomized clinical trials that compared routine early ultrasound to a policy of not routinely offering ultrasound Whitworth et al.
The researchers found that people who had an early ultrasound to date the pregnancy were less likely to be induced for a post-term pregnancy. In a large observational study that enrolled more than 17, pregnant people in Finland, researchers found that ultrasound at any time point between 8 and 16 weeks was more accurate than the LMP. There are several reasons why the LMP is usually less accurate than an ultrasound Savitz et al. LMP is less accurate because it can have these problems:.
The authors found that the most accurate time to perform an ultrasound to determine the gestational age was weeks. This was a more accurate result than any of the other ultrasound scans, and more accurate than the LMP. The accuracy of the ultrasound saw a significant decline starting at about 20 weeks. Using an estimated due date from either the LMP or an ultrasound at weeks led to a higher rate of pre- and post-term births.
Ultrasounds in the third trimester are less accurate than earlier ultrasounds or the LMP at predicting gestational age. All babies are about the same size early in pregnancy. The reverse is also true for babies that will be smaller than average at term—their due date might be moved to a later date. This could be risky if the baby is experiencing growth restriction, as growth-restricted babies have a higher risk of stillbirth towards the end of pregnancy.
Because of these problems with third trimester ultrasounds, the American College of Obstetricians and Gynecologists states that due dates should only be changed in the third trimester in very rare circumstances In the U.
In the past, researchers figured out the average length of a normal pregnancy by looking at a large group of pregnant people, and measuring the time from ovulation or the last menstrual period, or an ultrasound until the date the person gave birth—and calculating the average. However, this method is wrong and does not give us accurate results.
This method does not work because many people are induced when they reach 39, 40, 41, or 42 weeks. If you do include these induced people in your average, then you are including people who gave birth earlier than they would have otherwise, because they were not given time to go into labor on their own.
But this puts researchers in a bind, because if you exclude a person who was induced at 42 weeks from your study, then you are ignoring a pregnancy that was induced because it went longer—and by excluding that case, you artificially make the average length of pregnancy too short. There have been two studies that measured the average length of pregnancy using survival analysis:.
In a very important study published in , Smith looked at the length of pregnancy in 1, healthy women whose estimated due dates, as calculated by the first day of the last menstrual period, were perfect matches with estimated due dates from their first trimester ultrasound Smith, a.
In , Jukic et al. This was a smaller study—there were only healthy women, and they all gave birth between the years and However, this was also an important study, because researchers followed the participants even before conception and measured their hormones daily for six months Jukic et al. This means that the researchers knew the exact days that the participants ovulated, conceived, and even when their pregnancies implanted! After excluding women who had preterm births or pregnancy-related medical conditions, the final sample of women had a median time from ovulation to birth of days 38 weeks, 2 days after ovulation.
The median time from the first day of the last menstrual period to birth was days or 40 weeks, 5 days after the last menstrual period. The length of pregnancy ranged from 36 weeks and 6 days to one person who gave birth 45 weeks and 6 days after the last menstrual period. The 45 weeks and 6 days sounds really long… but this particular person actually gave birth 40 weeks and 4 days after ovulation. Her ovulation did not fit the normal pattern, so we know her LMP due date was not accurate. Women who had embryos that took longer to implant were more likely to have longer pregnancies.
Also, women who had a specific sort of hormonal reaction right after getting pregnant a late rise in progesterone had a pregnancy that was 12 days shorter, on average. Instead, it would be more appropriate to say that there is a normal range of time in which most people give birth.
About half of all pregnant people will go into labor on their own by 40 weeks and 5 days for first-time mothers or 40 weeks and 3 days for mothers who have given birth before. The other half will not. In , Oberg et al. They found that genetics has an incredibly strong influence on your chance of having a birth after 42 weeks:. Overall, researchers found that half of your chance for having a post-term birth comes from genetics. The risks of some complications go up as you go past your due date, and there are at least three important studies that have shown us what the risks are.
In their study, Caughey et al. However, when the researchers used a statistical method to control for the use of interventions, the risks still increased with gestational age. For more information about meconium, see this article by Midwife Thinking about meconium stained waters.
In this section, we will talk about how the risk of stillbirth increases towards the end of pregnancy. For example, if the absolute risk of having a stillbirth at 41 weeks was 1. But some people may consider the actual or absolute risk to still be low—1. Please see our handout on Talking about Due Dates for Providers for tips on how providers can discuss the risk of stillbirth.
The second important thing that you need to understand is that there are different ways of measuring stillbirth rates. Depending on how the rate is calculated, you can end up with different rates. Up until the s, some researchers thought that the risk of stillbirth past weeks was similar to the risk of stillbirth earlier in pregnancy.
So, they did not think there was any increase in risk with going past your due date. However, in , a researcher named Dr. Yudkin published a paper introducing a new way to measure stillbirth rates. Yudkin said that earlier researchers used the wrong math when they calculated stillbirth rates—they used the wrong denominator!
Yudkin, Wood et al. Instead, we need to know how many stillbirths happen at 41 weeks compared to all pregnancies and births at 41 weeks.
In other words, you have to include the healthy, living babies that have not been born yet in your denominator. When researchers began using this new formula to figure out stillbirth rates, they found something very surprising—the risk of stillbirth decreased throughout pregnancy, until it reached a low point at weeks, after which the risk started to rise again.
This finding—that the risk of stillbirth decreases throughout pregnancy, and then increases sometime after weeks—has been found many times by different researchers in different countries. In other words, there are higher rates of stillbirth earlier in pregnancy, then they go down until around weeks, after which they rise again.
Because the risk of stillbirth starts to go up even more at 40, 41, and 42 weeks, some researchers argue that although 40 weeks and days may be the physiological length of pregnancy, 40 weeks may be the functional length of a pregnancy.
And although the stillbirth rates may seem low overall, if you happen to be a parent who experiences the 1 in event at 42 weeks Muglu et al. Even after researchers began using the new way of calculating stillbirth rates, there was still controversy about the best way to calculate this new formula for measuring stillbirth rates.
Other researchers argued that most people and doctors! Hilder et al. They just want to know what the risk would be if they waited one more week until the next appointment, or even a few days. Boulvain et al. In the end, you will find that stillbirth rates vary from study to study, depending on whether the researchers report the actual stillbirth rate, or the open-ended stillbirth rate. Some of the researchers used open-ended stillbirth rates, and some of them used actual stillbirth rates.
All of the researchers found a relative increase in the risk of stillbirth as pregnancy advanced. To get an accurate picture of stillbirth in people who go past their due date, it would be best to look at studies that took place in more recent times. To see all of the other studies, click to view the entire table here. All 3 of these studies used the actual stillbirth rate—not the open-ended stillbirth rate. Two studies used ultrasound to calculate gestational age, and one study used the LMP.
The largest meta-analysis to date on risks of stillbirth and newborn death at each week of term pregnancies was published in Muglu et al.
The researchers included 13 studies 15 million pregnancies, nearly 18, stillbirths. The risk of stillbirth per 1, was 0. Based on their data, Muglu et al. To experience one additional stillbirth, there would need to be at least 2, people waiting for labor for one more week starting at 39 weeks.
At 40 weeks, 1, people would have to wait for labor for one more week to experience one additional stillbirth. At 41 and 42 weeks, only and people, respectively, would have to wait for labor for one more week to experience one additional stillbirth.
The researchers also found evidence that health care systems are failing Black mothers and babies—an alarming but common theme in health care research. Black mothers were 1. When they looked only at low-risk pregnancies, the risk of stillbirth was 0. Low-risk pregnancy was defined as pregnancies with a single baby, no congenital abnormalities, and no medical conditions in the mother. There was no additional risk of newborn death when giving birth between 38 and 41 weeks, but the risk of newborn death did increase beyond 41 weeks.
Other factors that do not necessarily cause stillbirth but may increase the risk of stillbirth, in general, include:. Of course, parents can still experience the stillbirth of a child even when none of these risk factors are present. To read more about theories of unexplained stillbirth, read this article here. However, up until recently, there was no research on this topic.
0コメント