Why difference in lmp and gestational age?

The EDD of a pregnant woman is used to decide if the baby is growing at an accurate pace or not. It is also needed to decide whether a baby needs induction to prevent long pregnancies. Furthermore, the induction of labour is offered to a woman routinely at 42 weeks of pregnancy, and if the EDD is way before, then the baby may be born when they are not fully prepared.

Therefore, one must check if their dating scan different to LMP or not. And if there is 4 weeks difference between LMP and Ultrasound, then one should change the due date to the date predicted by the ultrasound.

One can get an idea of the expected due date using ultrasound. However, if a woman wants to estimate her due date on her own, she can do so by following these steps -

The EDD calculation using LMP is accurate only when a woman has regular periods. One can check the validity of EDD from LMP by checking if there is a 3 Weeks difference in Edd by LMP and ultrasound date.

The EDD By Lmp Means will on be accurate only under perfect conditions. Perfect conditions mean that the woman is having a regular period, the ovulation occurs on the 14th day, and the baby has conceived right away. This is rarely the case in most pregnancies. Therefore it is extremely difficult to find the accurate due date using LMP. While ultrasound is considered the most trusted method of forecasting pregnancy due date. Furthermore, the scans in an ultrasound give the right measure of the child, which allows doctors to make accurate estimations of the baby’s age. However, to get an accurate ultrasound, one must get it done in the first trimester of the pregnancy.

When there is 1 week difference between LMP and ultrasound date, the ultrasound date is used for calculating the EDD. And when there is less than 5 days difference between LMP and ultrasound date, the LMP date is used to determine the EDD. This EDD determined in the first trimester should not be changed during the pregnancy.

On several occasions, a woman does not get an ultrasound scan in the first trimester and decides to go for an ultrasound between 18-20 weeks of the pregnancy. So if someone is going for an ultrasound at this time and in the result, there is 10 days difference between LMP and ultrasound date, then only a woman should change the due date to what the ultrasound results estimate.

There is usually a 2 weeks difference between LMP and Ultrasound. This is because in the first two weeks, dating from the LMP, the woman is not pregnant, but the body is preparing for ovulation as usual. However, in some cases, one can find a greater difference In LMP and Ultrasound scan because ovulation is not always a perfect science, and it can happen later than the usual date, which can affect the date of conception. If the dates in LMP Or Ultrasound 2 Weeks Different, one cannot rely on the LMP date, and they need to switch the EDD to the ultrasound date.

Gestational age (GA) is the expected tenure of someone's pregnancy and is calculated by adding forty weeks to the LMP date. Upon receiving the ultrasound report, one will find letters GA, indicative of the gestational age.

AUA stands for ultrasound age, which is used to calculate the baby's exact age. The only difference in a GA LMP Vs GA AUA comparison is that the gestational age from AUA, unlike GA LMP is the date which excludes the days between conception and the last period.

Gestational age helps to estimate a possible due date, inform obstetrical care and testing, and evaluate the baby's health at birth. It serves as a guideline to determine if the baby is growing as expected and when to perform certain prenatal screenings. Babies born smaller or bigger than expected for their gestational age may need to be monitored more closely.

Parents do not always know when conception occurred. Healthcare providers can determine weeks of gestation by looking at the mother's menstrual cycle and with the use of ultrasounds. Gestational age is calculated from the first day of the pregnant person's last menstrual period (LMP) to the present day. (Technically, gestational age includes the two weeks prior to conception, before the person is pregnant.)

Calendar calculations based on the last menstrual period assume the pregnant person has a regular 28-day cycle. Because that is often not the case, fetal ultrasounds help to provide more information to inform gestational age. In fact, first trimester ultrasounds of the embryo or fetus (up to and including 13 6/7 weeks of gestation) are the most accurate way to determine gestational age.

In the first trimester, ultrasound measures the length from the top of the head to the bottom of the baby's buttocks. This is the crown-rump length or CRL. In later stages of pregnancy, ultrasounds measure specific parts of the baby's body including the abdomen, head, and femur (thigh bone) to confirm gestational age and fetal growth.

In cases where assisted reproductive technology (ART) is used to conceive, the ART-derived gestational age is used to calculate the estimated date of delivery (EDD) or due date. For example, with in-vitro fertilization, doctors would use the age of the embryo and the date of the transfer along with ultrasounds to determine how far along the pregnancy is.

It is important to distinguish between gestational age and fetal age. While gestational age starts with the date of the LMP, embryonic age (and later fetal age) starts at the time of conception, when the sperm fertilizes the egg. Fetal age is two weeks behind gestational age and describes the actual age of the fetus.

Gestational age is important because it helps guide prenatal care. It is an essential starting point providers use to:

At birth, a baby's condition is evaluated to determine how the baby relates to their gestational age. The doctor looks at their:

Based on those factors and how they compare to their calendar age, the baby is considered small for gestational age (SGA), large for gestational age (LGA), or appropriate for gestational age (AGA). In terms of weight, full-term infants who are AGA weigh on average between 5.5 pounds and 8.75 pounds. Babies who are small or large may be monitored more closely for complications.

Doctors use the date of the mother's last menstrual period and first trimester ultrasounds to determine gestational age. In pregnancies resulting from assisted reproductive technologies like IVF, the embryo's age and the date of conception are used to calculate gestational age.

Ultrasounds in early pregnancy are the most accurate way to determine gestational age, especially for pregnant people with a history of irregular menstrual cycles.

A baby is considered large for gestational age (LGA) if they weigh over 4,000 grams (8.75 pounds) at birth. They may also be taller or have a larger head than an average baby of the same age and sex.

A baby is considered small for gestational age (SGA) if they weigh less than 2,500 grams (5.5 pounds). They may also be shorter or less developed than a baby who is considered an appropriate weight for gestational age.

Gestational age is the time beginning with the pregnant person's last menstrual period (LMP) to the present (and as a result, includes the two weeks before conception occurred). It refers to how far along the pregnancy has progressed. Gestational age is the number most people use when describing how many weeks pregnant they are. Fetal age, on the other hand, starts at conception and only describes the age of the developing fetus.

Gestational age is the time beginning with the pregnant person's last menstrual period (LMP) to the present (and as a result, includes the two weeks before conception occurred). It refers to how far along the pregnancy has progressed.