. 2009 Feb 27;4(2):e4624. doi: 10.1371/journal.pone.0004624

Table 1. Estimates of sex ratio at birth in Viet Nam, 1998–2007.

1998	Sex ratio at birth			Size of birth samples
Source	Annual surveys ^a		Survey of births ^c	Annual surveys ^a	2006 survey ^b	2007 survey ^b	Survey of births ^c
Method used	Last birth ^a	Birth history ^b		Last births	Birth history	Birth history
Year of birth
1998	107			39 733
1999	105.5^a	104.6		24 288	24 033	23 695
2000	109	104.8		26 350	26 984	26 734
2001	107	105.4		22 779	24 341	24 099
2002	104	107.5		24 096	22 996	23 093
2003	108	106.6		26 784	26 086	26 394
2004	106	106.6		24 145	24 209	24 612
2005	110	108.2		25 446	24 962	24 014
2006	111.6	111.7	108.7	24 499	5 651^d	24 536	1 478 082
2007		110.9	111.0			5 332^d	1 443 526

Estimates published in the annual Surveys of Population Change, Labour Force and Family Planning (General Statistics Office, Hanoi) except for 1999 (computed from the 2000 survey data).

Computed by the first author from the 2006 and 2007 annual survey data files.

Data for the survey of births in health centres conducted in 2007 and 2008 by the General Statistics Office and the Ministry of Health.

Only available for the first trimester.