Table 1.
Characteristics of study population by year, Flanders, 2002–11. Values are medians (10–90th centiles) unless stated otherwise
| Year | Total births | All preterm births | Mild preterm | Moderate preterm | Extreme preterm | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| No of births | Maternal age (years) | Birth weight (g) | % SGA | % LBW | % Rate | Birth weight (g) | % Rate | Birth weight (g) | % Rate | Birth weight (g) | % Rate | Birth weight (g) | |||||
| Spontaneous delivery | |||||||||||||||||
| 2002 | 38 658 | 29.3 (23.3–35.3) | 3320 (2690–3910) | 10.98 | 5.63 | 7.41 | 2510 (1480–3170) | 5.81 | 2650 (2120–3230) | 0.79 | 1985 (1390–2480) | 0.82 | 1220 (750–1795) | ||||
| 2003 | 38 990 | 29.4 (23.3–35.4) | 3318 (2690–3910) | 10.49 | 5.69 | 7.42 | 2520 (1535–3130) | 5.90 | 2650 (2100–3190) | 0.78 | 1940 (1440–2460) | 0.74 | 1195 (740–1793) | ||||
| 2004 | 42 077 | 29.4 (23.5–35.6) | 3330 (2705–3920) | 9.92 | 5.50 | 7.52 | 2550 (1495–3180) | 5.83 | 2680 (2110–3240) | 0.79 | 1990 (1490–2485) | 0.89 | 1250 (732–1800) | ||||
| 2005 | 43 290 | 29.4 (23.6–35.7) | 3330 (2705–3920) | 10.15 | 5.39 | 7.38 | 2520 (1470–3170) | 5.80 | 2655 (2090–3250) | 0.76 | 1963 (1483–2435) | 0.82 | 1160 (715–1700) | ||||
| 2006 | 45 003 | 29.4 (23.6–35.8) | 3330 (2700–3925) | 9.82 | 5.32 | 7.36 | 2540 (1530–3140) | 5.74 | 2660 (2100–3200) | 0.85 | 1940 (1475–2.400) | 0.76 | 1250 (720–1735) | ||||
| 2007 | 46 276 | 29.4 (23.6–35.8) | 3330 (2720–3920) | 9.83 | 5.12 | 6.93 | 2520 (1511–3145) | 5.37 | 2655 (2140–3200) | 0.79 | 1995 (1490–2450) | 0.77 | 1210 (740–1775) | ||||
| 2008 | 47 893 | 29.5 (23.6–35.9) | 3345 (2720–3940) | 9.24 | 5.22 | 7.15 | 2510 (1510–3130) | 5.58 | 2650 (2110–3200) | 0.78 | 1990 (1490–2400) | 0.79 | 1250 (712–1850) | ||||
| 2009 | 48 237 | 29.5 (23.6–35.9) | 3345 (2720–3940) | 9.69 | 5.15 | 6.98 | 2515 (1480–3150) | 5.38 | 2660 (2120–3220) | 0.82 | 1984 (1380–2400) | 0.78 | 1240 (750–1795) | ||||
| 2010 | 49 166 | 29.7 (23.8–35.9) | 3350 (2730–3940) | 9.24 | 4.85 | 6.84 | 2530 (1470–3135) | 5.28 | 2655 (2120–3200) | 0.76 | 1980 (1470–2470) | 0.81 | 1220 (705–1770) | ||||
| 2011 | 48 930 | 29.7 (23.8–36.0) | 3350 (2730–3940) | 9.62 | 4.89 | 6.80 | 2510 (1450–3145) | 5.26 | 2660 (2120–3220) | 0.72 | 1963 (1405–2418) | 0.82 | 1240 (720–1765) | ||||
| Total | 448 520 | 29.5 (23.6–35.8) | 3335 (2710–3930) | 9.86 | 5.26 | 7.16 | 2520 (1490–3150) | 5.58 | 2660 (2115–3215) | 0.78 | 1975 (1448–2430) | 0.80 | 1220 (730–1780) | ||||
| Overall delivery | |||||||||||||||||
| 2002 | 55 275 | 29.3 (23.2–35.3) | 3350 (2730–3950) | 10.74 | 4.91 | 5.99 | 2520 (1540–3180) | 4.74 | 2650 (2100–3250) | 0.59 | 1970 (1390–2460) | 0.61 | 1220 (750–1790) | ||||
| 2003 | 55 639 | 29.3 (23.2–35.4) | 3350 (2720–3950) | 10.34 | 4.89 | 5.98 | 2530 (1600–3140) | 4.84 | 2640 (2090–3200) | 0.59 | 1940 (1440–2460) | 0.55 | 1200 (740–1790) | ||||
| 2004 | 58 041 | 29.4 (23.4–35.7) | 3360 (2740–3960) | 9.90 | 4.87 | 6.26 | 2555 (1540–3180) | 4.96 | 2680 (2100–3240) | 0.62 | 1990 (1490–2493) | 0.68 | 1250 (730–1800) | ||||
| 2005 | 59 368 | 29.4 (23.5–35.7) | 3360 (2740–3960) | 10.08 | 4.73 | 6.19 | 2535 (1510–3180) | 4.96 | 2660 (2080–3260) | 0.61 | 1970 (1490–2450) | 0.62 | 1160 (713–1700) | ||||
| 2006 | 60 871 | 29.4 (23.5–35.8) | 3360 (2730–3960) | 9.81 | 4.73 | 6.16 | 2540 (1560–3155) | 4.90 | 2660 (2090–3210) | 0.66 | 1935 (1470–2400) | 0.60 | 1260 (720–1740) | ||||
| 2007 | 61 847 | 29.4 (23.5–35.9) | 3360 (2740–3960) | 9.77 | 4.64 | 5.86 | 2520 (1560–3145) | 4.61 | 2650 (2120–3200) | 0.64 | 1990 (1480–2430) | 0.61 | 1210 (740–1770) | ||||
| 2008 | 63 999 | 29.5 (23.5–36.0) | 3370 (2750–3980) | 9.30 | 4.69 | 6.11 | 2520 (1550–3145) | 4.84 | 2650 (2100–3210) | 0.63 | 1990 (1490–2410) | 0.63 | 1255 (710–1850) | ||||
| 2009 | 63 415 | 29.5 (23.5–36.0) | 3370 (2740–3975) | 9.71 | 4.74 | 6.07 | 2520 (1528–3150) | 4.77 | 2655 (2090–3220) | 0.67 | 1980 (1385–2400) | 0.63 | 1240 (750–1798) | ||||
| 2010 | 64 372 | 29.6 (23.7–36.0) | 3375 (2750–3980) | 9.43 | 4.59 | 5.98 | 2530 (1520–3135) | 4.69 | 2650 (2090–3195) | 0.65 | 1975 (1470–2465) | 0.64 | 1220 (705–1770) | ||||
| 2011 | 64 050 | 29.7 (23.8–36.0) | 3370 (2750–3980) | 9.65 | 4.52 | 5.88 | 2510 (1490–3155) | 4.62 | 2650 (2090–3220) | 0.61 | 1955 (1400–2408) | 0.65 | 1240 (712–1765) | ||||
| Total | 606 877 | 29.5 (23.5–35.8) | 3360 (2740–3965) | 9.85 | 4.73 | 6.04 | 2530 (1540–3155) | 4.79 | 2650 (2100–3220) | 0.63 | 1970 (1450–2430) | 0.62 | 1220 (725–1780) | ||||
SGA = Small for gestational age. LBW = Low birth weight (<2500 g).
Preterm categories: mild = 34–36 weeks gestation, moderate = 32–33 weeks, extreme= <32 weeks.
Parity was constant over the study period: median (10–90th centile) = 2 (1–3).