33 Weeks-Estimated Fetal Weight

Good God: Seahorse grows by the minute. Today’s 33 week scan revealed one stout little critter who now weighs just under 2.5kg. WITH 7 MORE WEEKS OF GROWTH TO GO…what size will Seahorse come out?

Exactly 12 weeks pregnant: 54kg. No weight gain as yet, but wait for it...

Exactly 12 weeks pregnant: 54kg. No weight gain as yet, but wait for it…

Secretly I am a gloating mumma-bear even though the brunt of this weight is felt by my aching back and squashed transverse colon of the large intestine which pushes up through my diaphragm and lungs, causing breathlessness and discomfort all at once. Still, I love being pregnant with a hefty bebe…

Seahorse at 4.5 months gestation. Growing growing growing...

Seahorse at 4.5 months gestation. Growing growing growing…

Needless to say, Erroll’s pride at his thriving baby-on-board is on show, but just for me. He never exults in front of others, just professes his deep attachment already to his unborn child with rubs on the belly and big smiles when there is a kick or a punch.

31 weeks pregnant and weighing in at 68kg: 14kg added!

31 weeks pregnant and weighing in at 68kg: 14kg added!

Estimated fetal weight calculations are based on the 4 common fetal measurements:

  • Biparietal diameter (BPD)-diameter between the fetus’ two parietal bone of the head
  • Head circumference (HC)-measurement of head around its largest area: the distance from above the eyebrows and ears and around the back of the head 
  • Femur length (FL)-the longest, heaviest and by most measures the strongest bone in the body. Its length is 26% of a human’s height, and
  • Abdominal circumference (AC)-measured at the level of the liver and stomach, including the left portal vein at the umbilical region.

In general, about 2 in 3 actual fetal weights will be about 16% plus/minus the average. Actual weights can often be higher or lower than the 16% +/-.  One standard deviation encompasses about 68% of all cases, so about 2 in 3 babies will weigh within the one standard deviation range. Two standard deviations include about 95% of all babies, so the range of two standard deviations would include 95% of all actual weights, but still about 5% of babies would either be bigger (2.5%) or smaller (2.5%).

I do wonder quietly to myself whether Seahorse shall come into this world 3 standard deviations above the ‘normal’ fetal weights charted in the medical books. If you ask my bulging belly and hunched back, that would be a definite yes; we may well have a new world record come early December 2013…

Leave a Reply