Number of births
|
554,689
|
546,201
|
524,058
|
508,124
|
500,367
|
502,124
|
492,921
|
500,404
|
490,383
|
487,818
|
Number of preterm births
|
50,108
|
48,796
|
45,394
|
42,909
|
42,080
|
41,839
|
40,885
|
40,767
|
40,947
|
41,555
|
Percentage of preterm births
|
9.0
|
8.9
|
8.7
|
8.4
|
8.4
|
8.3
|
8.3
|
8.2
|
8.4
|
8.5
|
Variable
|
Maternal age (years)
|
< 20
|
9.1
|
8.8
|
8.4
|
8.2
|
8.2
|
8.1
|
8.0
|
8.0
|
8.0
|
8.3
|
20–24
|
8.1
|
8.0
|
7.7
|
7.6
|
7.4
|
7.4
|
7.4
|
7.1
|
7.5
|
7.7
|
25–29
|
8.2
|
8.1
|
7.8
|
7.6
|
7.6
|
7.6
|
7.6
|
7.3
|
7.5
|
7.7
|
30–34
|
9.0
|
8.9
|
8.6
|
8.4
|
8.4
|
8.3
|
8.1
|
8.0
|
8.2
|
8.2
|
35–39
|
10.7
|
10.6
|
10.4
|
10.0
|
10.0
|
9.7
|
9.7
|
9.5
|
9.7
|
9.9
|
40–54
|
14.2
|
14.4
|
14.1
|
13.5
|
13.6
|
13.3
|
13.2
|
13.2
|
13.5
|
13.6
|
Maternal race and ethnicity
|
Hispanic
|
8.6
|
8.4
|
8.2
|
8.0
|
8.1
|
8.1
|
8.2
|
8.2
|
8.4
|
8.7
|
Whitea
|
9.0
|
8.8
|
8.5
|
8.2
|
8.0
|
7.6
|
7.7
|
7.3
|
7.5
|
7.6
|
Asianb
|
8.8
|
8.8
|
8.8
|
8.3
|
8.4
|
8.3
|
8.0
|
7.5
|
7.8
|
8.1
|
Pacific Islanderc
|
10.7
|
10.3
|
9.4
|
10.3
|
8.6
|
8.8
|
8.9
|
9.1
|
10.8
|
9.6
|
African American
|
12.7
|
13.0
|
12.3
|
12.2
|
11.7
|
11.9
|
11.6
|
11.9
|
11.7
|
11.4
|
Multiple race
|
9.8
|
9.1
|
9.2
|
9.1
|
8.6
|
9.1
|
8.7
|
9.0
|
8.9
|
9.3
|
American Indiand
|
10.4
|
10.6
|
9.3
|
10.0
|
8.8
|
8.8
|
10.0
|
8.9
|
10.1
|
10.3
|
Other/unknowne
|
12.8
|
13.0
|
11.7
|
12.2
|
12.0
|
11.3
|
11.1
|
11.6
|
10.9
|
10.5
|
Maternal education level
|
Less than high school diploma
|
8.8
|
8.7
|
8.5
|
8.3
|
8.4
|
8.4
|
8.7
|
9.0
|
9.3
|
9.5
|
High school diploma
|
8.9
|
9.0
|
8.5
|
8.4
|
8.4
|
8.2
|
8.2
|
8.1
|
8.3
|
8.6
|
Some college or associate degree
|
9.4
|
9.1
|
8.8
|
8.8
|
8.7
|
8.5
|
8.5
|
8.3
|
8.5
|
8.6
|
Bachelor’s degree or higher
|
8.9
|
8.7
|
8.5
|
8.0
|
7.9
|
7.9
|
7.6
|
7.3
|
7.5
|
7.6
|
Unknown
|
10.9
|
11.3
|
10.6
|
10.5
|
10.4
|
10.2
|
10.5
|
10.2
|
9.8
|
10.0
|
Maternal nativity
|
Foreign-born
|
8.2
|
8.2
|
8.0
|
7.8
|
8.0
|
7.9
|
7.9
|
7.8
|
8.1
|
8.4
|
United States-born
|
9.7
|
9.5
|
9.1
|
8.9
|
8.7
|
8.6
|
8.5
|
8.3
|
8.5
|
8.6
|
Maternal demographic region
|
Central Coast
|
8.1
|
8.1
|
7.7
|
7.7
|
7.7
|
7.4
|
7.8
|
7.4
|
7.9
|
7.9
|
Greater Bay Area
|
8.5
|
8.6
|
8.6
|
8.4
|
8.1
|
8.4
|
8.2
|
7.9
|
8.1
|
8.3
|
Inland Empire
|
9.5
|
9.0
|
8.9
|
8.6
|
8.4
|
8.7
|
8.5
|
8.3
|
8.5
|
8.8
|
Los Angeles County
|
9.3
|
9.3
|
8.8
|
8.6
|
8.7
|
8.5
|
8.5
|
8.4
|
8.7
|
8.8
|
Northern and Sierra
|
8.4
|
8.0
|
7.6
|
7.4
|
7.6
|
7.5
|
7.7
|
7.4
|
8.0
|
8.1
|
Orange County
|
8.7
|
8.3
|
8.5
|
8.1
|
8.2
|
7.8
|
7.6
|
7.3
|
7.5
|
7.9
|
Sacramento area
|
8.8
|
8.5
|
8.3
|
8.2
|
8.1
|
8.0
|
7.9
|
8.1
|
8.0
|
8.1
|
San Diego area
|
9.5
|
9.0
|
9.0
|
8.4
|
8.4
|
8.3
|
8.1
|
8.2
|
8.0
|
8.4
|
San Joaquin Valley
|
9.4
|
9.7
|
9.1
|
8.9
|
9.0
|
8.8
|
8.9
|
8.8
|
9.0
|
9.0
|
Source of prenatal care payment
|
Private
|
9.2
|
9.0
|
8.8
|
8.7
|
8.5
|
8.4
|
8.2
|
8.1
|
8.2
|
8.3
|
Medi-Cal
|
8.7
|
8.6
|
8.3
|
8.1
|
8.1
|
8.2
|
8.3
|
8.2
|
8.5
|
8.7
|
WIC Participation
|
No
|
9.5
|
9.4
|
9.1
|
8.9
|
8.7
|
8.6
|
8.4
|
8.1
|
8.3
|
8.4
|
Yes
|
8.6
|
8.5
|
8.3
|
8.0
|
8.2
|
8.1
|
8.2
|
8.2
|
8.4
|
8.6
|
First trimester prenatal care initiation
|
No
|
9.1
|
8.6
|
8.3
|
8.3
|
8.2
|
8.2
|
8.2
|
8.1
|
8.2
|
8.5
|
Yes
|
8.9
|
8.9
|
8.6
|
8.4
|
8.4
|
8.3
|
8.2
|
8.1
|
8.3
|
8.4
|
Parity
|
Primiparous
|
8.4
|
8.2
|
8.0
|
7.8
|
7.7
|
7.7
|
7.7
|
7.4
|
7.7
|
7.8
|
Multiparous (2–5)
|
9.3
|
9.2
|
8.9
|
8.7
|
8.6
|
8.5
|
8.4
|
8.4
|
8.5
|
8.7
|
Multiparous (6–12)
|
14.9
|
15.2
|
15.0
|
14.6
|
13.9
|
14.6
|
14.7
|
15.3
|
15.3
|
15.6
|
Plurality
|
Singleton births
|
8.0
|
7.9
|
7.5
|
7.4
|
7.3
|
7.3
|
7.2
|
7.1
|
7.3
|
7.5
|
Multiple births
|
60.9
|
59.2
|
59.0
|
57.4
|
57.4
|
56.0
|
55.0
|
54.4
|
55.8
|
56.8
|
Maternal smoking during both first and second trimesters
|
No
|
8.9
|
8.8
|
8.6
|
8.4
|
8.3
|
8.2
|
8.2
|
8.1
|
8.2
|
8.4
|
Yes
|
15.7
|
15.0
|
14.6
|
14.2
|
14.8
|
15.6
|
16.4
|
15.5
|
16.9
|
17.9
|
Prepregnancy body mass index (kg/m2)
|
Underweight (≤18.5)
|
9.7
|
10.0
|
9.4
|
9.0
|
8.9
|
8.8
|
8.6
|
8.5
|
8.4
|
8.7
|
Normal (18.5–24.9)
|
8.5
|
8.4
|
8.1
|
7.9
|
7.9
|
7.7
|
7.7
|
7.4
|
7.5
|
7.7
|
Overweight (25.0–29.9)
|
8.8
|
8.5
|
8.3
|
8.1
|
8.3
|
8.2
|
8.1
|
8.1
|
8.2
|
8.6
|
Obese I (30.0–34.9)
|
9.6
|
9.3
|
9.1
|
9.0
|
8.9
|
8.8
|
8.9
|
9.0
|
9.3
|
9.3
|
Obese II (35.0–39.9)
|
10.1
|
10.1
|
10.4
|
9.4
|
9.1
|
10.1
|
9.4
|
9.6
|
10.1
|
10.1
|
Obese III (≥ 40)
|
10.8
|
11.2
|
10.0
|
11.2
|
10.3
|
10.1
|
10.4
|
10.0
|
10.6
|
10.4
|