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how to calculate the delivery date of a baby

how to calculate the delivery date of a baby

When pregnancy is certain, a few issues would surely come into your mind. Other than the suspense about the gender of your baby, you should also start to wonder how to calculate the delivery date of a baby simply because you want to plan for your delivery. Moreover, your workmates and friends may ask you and your husband about the due date. While the target date of delivery can greatly help you in planning your baby’s birth, remember there is no precise method of forecasting the exact time and date of the birth. This is because, often times, every pregnancy’s due date carries a two week margin of error. Studies show that only around four to five percent of pregnant women actually give birth on their calculated due dates. To most moms, the pregnancy experience can lead to anxiety. One of the many ways to relieve such a feeling is to estimate the delivery date. If you are feeling that way now, the following calculation methods may help you.

  1. Use the Naegele’s Rule. Many doctors use this method to determine the due date of their pregnant clients.

    is rule presupposes that you have regular 28-day cycle and based on such cycle you must have ovulated during the 14th day. Recall your last period and record the first day, and then subtract three months from it. On the result, add one year and seven days. The result is your approximate delivery due date. Take note that this method is applicable only if you have 28-day cycle, which means your menstrual period is not irregular.

  2. Use the Mittendorf Williams Rule. This rule, which was discovered by Mittendorf sometime in the year 1990, relies on two conditions: you are a Caucasian pregnant woman, and this is your first pregnancy. Record the first day of your latest menstrual period and subtract three months from it. On the result, add another 15 days to get your estimated due date. Roughly, it will take 288 days more or less from the first day of your last period to deliver your baby.

    In case this is not your first pregnancy or you are not Caucasian, just add 10 days instead of 15 days. In truth, many women found this due date calculation method much more accurate than the other available methods.

  3. Use the 40 weeks estimate. This is based on the statement made by the American Pregnancy Association. The basis still relies on the first day of your latest menstrual period to determine the date when your baby is coming. On the first day, just add 40 weeks to get the estimated due date. Roughly, it will take around 280 days more or less to finally see your newborn baby.

    For instance, if your latest cycle commenced on October 1, week one would fall on October 8, week two would be on October 15, week three would be on October 22, and so on and so forth until you get to the 40th week. The last week will be your calculated delivery due date.

  4. Use the 38 weeks plus three-day estimate. This rule is useful if you are not having sexual intercourse too often. Recall the last time you had sexual contact with your partner and then add 38 weeks plus another three days. The result is the calculated due date of your baby. Roughly, that is only around 270 days to see deliver your baby. The 38 weeks is intended for the gestation period after conception while the three days is for the cushion. In most cases, the sperm can survive for only 72 hours while swimming toward the egg.

  5. Use the 38 weeks estimate from the ovulation day. This other method of estimating your due date is applicable only if your menstrual period is somewhat irregular. Your ovulation period can happen around 14 days prior to your period. If you are planning to get pregnant, you can use ovulation predictor or try to be sensitive of your physical sensations when ovulating. From that day, just add 38 weeks to have a rough estimate of your delivery date.

You can try any of the methods discussed on how to calculate delivery date of baby. While the result of your calculation may not be your exact delivery date, at least you will have an approximation. Take note, however, while there are pregnancies that can last for more than 42 weeks, there are also premature pregnancies which last for only 37 weeks at most. Cases like these happen because of several factors like parental care, pre-natal nutrition of the pregnant woman, ethnicity as well as the age of the pregnant mother.


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