Table 1.

Pregnancies in subjects screened at school (up to Dec 2015)

Maternal genotype	Total pregn.	Pregnant <screening	Twins (pairs)	Genotype of singleton births
				AA	AS	AC	SS	SC	Sβthal	Variants	Unknown	‘Eligible’ pregnancies
First pregnancy
AA	1742	91	10	1473	84	35	0	0	0	0	49	1641
AS	231	13	2	105	104	1	5	1	0	0	0	216
AC	78	2	1	30	3	37	0	4	0	0	1	75
Aβthal	25	0	0	21*	2	0	0	0	1	0	1	25
Total	2076	106	13	1629	193	73	5	5	1	0	51	1957
Second pregnancy
AA	286	1	3	257	11	8	0	0	0	2	4	282
AS	33	0	1	15	17	0	0	0	0	0	0	32
AC	11	0	0	6	0	5	0	0	0	0	0	11
Aβthal	4	0	0	4*	0	0	0	0	0	0	0	4
Total	334	1	4	282	28	13	0	0	0	2	4	329
Third pregnancy
AA	26	0	1	23	0	0	0	0	0	0	2	25
AS	2	0	0	2	0	0	0	0	0	0	0	2
AC	0	0	0	0	0	0	0	0	0	0	0	0
Aβthal	0	0	0	0	0	0	0	0	0	0	0	0
Total	28	0	1	25	0	0	0	0	0	0	2	27
Fourth pregnancy
AA	4	0	0	3	1	0	0	0	0	0	0	4
Grand total	2442	107	18	1939	222	86	5	5	1	2	57	2317

*For mothers with beta thalassaemia trait (Aβthal), these would be an AA phenotype, since approximately half would be Aβthal