Question 1

at what gestational age of fetus should the bpd measure approximately 4.1cm (41mm)?

Accepted Answer

BPD: Well we use more than just bpd to calculate the gestational age.  Head circ.,  femur length, and abdominal circ.  Also go into the calculation.  However, 4.1cm bpd is consistent with about 17 weeks 4 days.

Question 2

8wks measurements for a fetus is 1/2 in right? if so why did doc say i'm 8 w when fetus measures 1.7in?

Accepted Answer

Measurement in cm?: You're right, expected length of an 8w fetus is roughly 0.6in. This is about 1.6cm. Wonder if this is just a matter of using different units to describe the same thing.

Question 3

if u went for a 12 wk u/s and it showed the measurements of a 9 wk old fetus, is this enough of a difference to change the due date?

Accepted Answer

Yes: A 9 week sonogram is accurate within about 5 days. In your case your sonogram would be used to calculate your due date.

Question 4

why are fetal measurements measured by weeks plus days and not just by weeks? are the # of days just as important to determine gestational age?

Accepted Answer

Precision: By convention gestational age is stated in weeks.  For precision and accuracy weeks and days are usually indicated when specifying a gestational age.  For example, some tests may be done at 15 weeks but not at 14 weeks and 6 days - so the number of days is important as well.

Question 5

u/s on 1/20/14 gave measurement of 11w4d measuring the fetus at 4.8 cm. could 11/25/13 be conception date? what is the accurate conception date?

Accepted Answer

11/14/13: Based on the information you provided, the 'average' date of conception would be appx 11/14/13.  While 11/25 could be the conception date, it's highly unlikely.  Most first trimester ultrasounds are the most accurate ultrasound we have for dating a pregnancy.  Typically standard deviation of error is +/- 5 days.  Which would be as early as 11/9 or as late as 11/19.  Thus, 11/25 is an outlier.

Question 6

6 week 2 day fetus 
is a heartbeat 100 and 4mm measurement ok or is heartbeat too slow?

Accepted Answer

Can be ok: this heart rate can be ok, but recheck with sonos to be sure

Question 7

how accurate are the charts with crown rump fetus measurements? what does it mean being in the 5th, 50th and 95th percentile?

Accepted Answer

Very accurate: Those charts are compilations of hundreds of thousands of data points, and are generally fairly accurate.  Those percentiles are for averaged norms at those levels.

Question 8

are the measurements that precise on ultrasounds that it can show the difference between a 12wk fetus and a  fetus that is  12wks and  4  days?

Accepted Answer

No.: At 12 weeks, the estimated accuracy of ultrasound measurements (crown-rump length or crl) is +/- 7 days. Take Folic Acid 1-5 mg daily and best of luck!

Question 9

can the measurements of an 8or9 wk fetus measure "big" and be mistaken for a 12wk fetus? do fetuses have similar growth patterns at this early stage?

Accepted Answer

No and Yes: First trimester ultrasounds are very accurate for establishing your due date due the small variation in fetal growth at this stage.

Question 10

what are good results for a fetal fibronectin measurement?

Accepted Answer

Negative.: Feal fibronectin is a protein that should not be detected at the cervix - unless labor/delivery is impending. Negative ffn has been used to reassure women and obstetricians that delivery is not likely within a week in cases of preterm labor. Most mfm experts doubt its clinical usefulness, as most of the time it is the maternal cervical examination and not the ffn that dictates medical management.

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Doctor answers about:

Bpd measurement fetal

A member asked:

At what gestational age of fetus should the bpd measure approximately 4.1cm (41mm)?

A member asked:

8wks measurements for a fetus is 1/2 in right? if so why did doc say i'm 8 w when fetus measures 1.7in?

A member asked:

If u went for a 12 wk u/s and it showed the measurements of a 9 wk old fetus, is this enough of a difference to change the due date?

A member asked:

Why are fetal measurements measured by weeks plus days and not just by weeks? are the # of days just as important to determine gestational age?

A member asked:

U/s on 1/20/14 gave measurement of 11w4d measuring the fetus at 4.8 cm. could 11/25/13 be conception date? what is the accurate conception date?

A member asked:

6 week 2 day fetus is a heartbeat 100 and 4mm measurement ok or is heartbeat too slow?

A member asked:

How accurate are the charts with crown rump fetus measurements? what does it mean being in the 5th, 50th and 95th percentile?

A member asked:

Are the measurements that precise on ultrasounds that it can show the difference between a 12wk fetus and a fetus that is 12wks and 4 days?

A member asked:

Can the measurements of an 8or9 wk fetus measure "big" and be mistaken for a 12wk fetus? do fetuses have similar growth patterns at this early stage?

A member asked:

What are good results for a fetal fibronectin measurement?

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