Table 2.

Algorithm for the adjustment of the estimated date of conception

Calculation around EDC as Reported by the Site	LMP Reported	Interpretation	Method for Estimating/Adjusting EDC	3HP (n = 31) n	9H (n = 56) n	Total (n = 87) n (%)
EDD(r) − EDC(r) = 266 ± 1 d	Yes or No	EDC reported was consistent	Accepted as reported	3	11	14 (16.1)
EDC(r) − (LMP + 14) = n ± 55 d	Yes	EDC reported was not consistent, used LMP	EDC estimated as, EDC = LMP + 14	13	18	31 (36.5)
1) EDD(r) − DOB(r) in live birth = n ± 44 d, or	No	EDC reported was not consistent, used EDD	EDC estimated as, EDC = EDD − 266	13	24	37 (42.5)
2) 233 < = EDD(r) − EDC(r) in non-live birth ≤283
EDD(r) − DOB(r) = n + 48 d	No	EDC reported was not consistent, used reported gestational age at birth	EDC estimated as, EDC = DOB − (gestational age in weeks × 7)	1	0	1 (1.1)
EDD(r) − DOB(r) = n ≤93 or EDD(r) − EDC(r), n ≥300	No	EDC reported was not consistent, used DOB	EDC estimated as, DOB − 266	1	3	4 (4.6)

Definition of abbreviations: 3HP = 12-dose once-weekly regimen of isoniazid (900 mg) plus rifapentine (900 mg); 9H = 9-month daily isoniazid (300 mg); DOB = date of birth; DOB(r) = DOB reported by the site; EDC = estimated date of conception; EDC(r) = EDC reported by the site; EDD = estimated delivery date; EDD(r) = EDD reported by the site (e.g., if a child was born prematurely, the calculation of EDD − 266 is still considered accurate, as EDD was calculated by the clinician at enrollment, most likely using LMP; however, LMP was not reported); LMP = last menstrual period.