Table 1.

Characteristics of neural tube defect cases and controls in stage 1 (n = 18)^a.

Characteristic	Cases (n = 10)	Controls (n = 8)	Pb
Gestational week, mean (SD)	25.1 (7.6)	25.6 (8.9)	0.907
Gender, n (%)c
Male	4 (44.4)	3 (37.5)	0.772
Female	5 (55.6)	5 (62.5)

^aThe total number may not be equal to the number of cases or controls due to missing or unknown data.

^bIndependent samples test for gestational week; Pearson's χ² test for gender.

^cOne case with missing information on gender.