Can fetal age be more than gestational age?

Asked By: Zohartze Quagliozzi | Last Updated: 7th January, 2020
Category: family and relationships pregnancy
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Babies are called large for gestational age if they weigh more than expected for their gestational age (weeks of pregnancy) at birth. Diabetes is the most common cause of babies who are large for gestational age. If a baby is too large to fit through the birth canal easily, delivery can be difficult.

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Then, do doctors go by gestational age or fetal age?

While gestational age is measured from the first day of your last menstrual period, fetal age is calculated from the date of conception.

Additionally, how do you calculate fetal age? Gestational Age by LMP is calculated from the first day of the last menstrual period. EDD by LMP is calculated by adding 280 days (40 weeks) to the first day of the last menstrual period. Gestational Age by US is measured by ultrasound (US) on the Ultrasound Date.

Also asked, can gestational age be off by 2 weeks?

A pregnancy is formally considered as beginning on the first day of the mother's last menstrual period (LMP). An infant born before 37 completed weeks' gestation is considered premature. It is possible for gestational age to be inaccurate by up to 2 weeks, even with an accurate LMP date confirmed by other tests.

What is the gestational age of my baby?

Gestational age is the common term used during pregnancy to describe how far along the pregnancy is. It is measured in weeks, from the first day of the woman's last menstrual cycle to the current date. A normal pregnancy can range from 38 to 42 weeks. Infants born before 37 weeks are considered premature.

25 Related Question Answers Found

Does ultrasound determine fetal age or gestational age?

Ultrasound measurement of the embryo or fetus in the first trimester (up to and including 13 6/7 weeks of gestation) is the most accurate method to establish or confirm gestational age (3, 4, 7–10).

Can an ultrasound be wrong about gestational age?

Third-trimester ultrasound (beyond 28 0/7 weeks) is the most inaccurate method for pregnancy dating with an accuracy of +/- 21-30 days[1]. One major concern with third trimester dating ultrasound is underestimating the gestational age of a growth-restricted fetus[1].

Do they add 2 weeks to an ultrasound?

Ultrasounds in Later Pregnancy
As the pregnancy progresses, the accuracy of an ultrasound for predicting due dates decreases. Between 18 and 28 weeks of gestation, the margin of error increases to plus or minus two weeks. After 28 weeks, the ultrasound may be off by three weeks or more in predicting a due date.

How accurate is the gestational age?

The baby can be measured as early as 5 or 6 weeks after the mother's last menstrual period. Measuring the baby using ultrasound is most accurate in early pregnancy. It becomes less accurate later in pregnancy. The best time to estimate gestational age using ultrasound is between the 8th and 18th weeks of pregnancy.

Why do doctors go by your last period?


If you were having regular periods before pregnancy, your doctor will calculate your due date based off of your last menstrual period. This goes back to the fact that in order to get pregnant, your body ovulated—or released an egg—roughly in the middle of your cycle and it was fertilized by sperm.

Do all babies grow at same rate?

Just as each child grows and matures at different rates and at different times, so does that same child as it begins its life in the womb. The chart provided below provides benchmarks for most normal pregnancies. However, each fetus develops differently.

Why do doctors add two weeks to pregnancy?

The first day of your menstrual period is called 'Day 1' of your menstrual cycle, and ovulation typically occurs on day 14, which is the time a woman is most likely to conceive. All of which is to say that if a baby was conceived on day 14, the convention is to date the pregnancy back two weeks.

Why pregnancy is counted from last period?

Pregnancy is calculated from this day because each time a woman has a period, her body is preparing for pregnancy. Counting from the LMP, most women are pregnant an average of 280 days.

What does it mean if baby is measuring behind?

Small for gestational age means a baby is smaller than expected for the number of weeks of pregnancy. When the unborn baby does not get enough oxygen or nutrients during pregnancy, he or she does not grow as much as normal. The condition is often suspected before birth. Prenatal care is important in all pregnancies.

Can a dating ultrasound be 2 weeks off?


It is usually offered to pregnant women from 10 weeks to 13 weeks gestation, but can be carried out any time from 6 weeks. If you have had bleeding during your pregnancy or you have had previous miscarriages, your doctor or midwife may recommend an early dating scan from 6 to 10 weeks gestation.

What causes baby to measure behind?

Intrauterine growth restriction (IUGR) refers to a condition in which an unborn baby is smaller than it should be because it is not growing at a normal rate inside the womb. Delayed growth puts the baby at risk of certain health problems during pregnancy, delivery, and after birth. They include: Low birth weight.

How do you calculate gestational age with irregular periods?

Generally, your doctor orders an ultrasound to determine the gestational age of your baby when there's a history of irregular periods, when the date of your LMP is uncertain, or when conception occurred despite oral contraceptive use.

Is conception date or last period more accurate?

Because few women know the exact day they ovulated or conceived, an ultrasound done in the first trimester of pregnancy has been shown to the be the most accurate way to date a pregnancy. If an ultrasound date in the first trimester differs from your LMP date by seven days or more, we would go with the ultrasound.

How accurate is a 20 week ultrasound for due date?

The evidence suggests that ultrasound is more accurate than the last menstrual period date in predicting when the baby will be born—but only in the first trimester (weeks 1 through 12) and early second trimester (until roughly 20 weeks).

How do doctors calculate pregnancy?


A typical pregnancy lasts, on average, 280 days, or 40 weeks—starting with the first day of the last normal menstrual period as day 1.

Calculating a Due Date
  • First, determine the first day of your last menstrual period.
  • Next, count back 3 calendar months from that date.
  • Lastly, add 1 year and 7 days to that date.

What is BPD HC AC FL in pregnancy?

Biparietal diameter (BPD) is one of the basic biometric parameters used to assess fetal size. BPD together with head circumference (HC), abdominal circumference (AC), and femur length (FL) are computed to produce an estimate of fetal weight.

What week is safe to give birth?

Babies are safest when they are born at term. Term is anywhere between 37 and 42 weeks of pregnancy. Before 37 weeks, babies can experience a range of health issues.