Table 3.
Biometric parameter used to establish gestational age in GRAPHSa.
| Gestational age | Biometric parameter used to establish trial estimated delivery date |
| Less than 14 0/7 weeks gestation | CRL, average of two best imagesc |
| 14 0/7 through 15 6/7 weeks gestationb | BPD, average of two best imagesc |
| 16 0/7 weeks gestation and greater | BPD +FL, average of two best BPD and two best FL imagesc |
aGRAPHS: Ghana Randomized Air Pollution Health Study.
bResearch midwives are encouraged to obtain both CRL and BPD for pregnancies where gestational age appears to be in the 13-15 week range.
cBest images are determined by study obstetrician following review of all images.