Table 2

Baseline characteristics by smoking status for singleton births in the MATEX cohort (1991–2016)

AllNon-smokerQuit smoking during first trimesterContinued smoking after first trimester
1 376 77884.5% (1 163 225)3.5% (47 819)12% (165 734)
Mother
Mean (SD)Mean (SD)Mean (SD)Mean (SD)
 Age (years)29.39 (5.34)29.78 (5.16)27.18 (5.43)27.3 (5.83)
 Parity (nulliparous)59.5 (818 294)39.4 (458 010)58.8 (28 097)43.2 (71 629)
 Marital status (married or partnership)62 (846 557)66.8 (771 065)35.9 (17 039)35.7 (58 453)
 Socioeconomic status% (count)% (count)% (count)% (count)
 Upper white collar worker14.9 (205 770)16.8 (195 402)6.4 (3081)4.4 (7287)
 Lower white collar worker36.4 (501 780)37.4 (435 623)30.9 (14 786)31 (51 371)
 Blue collar worker15.1 (207 962)13.2 (153 567)19.2 (9189)27.3 (45 206)
 Other16.8 (231 481)16.3 (189 157)17.2 (8229)20.6 (34 095)
 Missing16.7 (229 785)16.3 (189 476)26.2 (12 534)16.8 (27 775)
Child
Mean (SD)Mean (SD)Mean (SD)Mean (SD)
 Gestational age (days)278.66 (12.05)278.74 (11.85)279.34 (12.11)277.87 (13.29)
 Birth weight (g)3549.45 (542.2)3573.19 (536.38)3540.62 (535.37)3385.36 (556.1)
 Body length (cm)50.21 (2.43)50.32 (2.4)50.12 (2.39)49.5 (2.59)
 Head circumference (cm)*34.94 (1.64)34.99 (1.62)34.91 (1.65)34.55 (1.71)
 Preterm birth% (count)% (count)% (count)% (count)
 Preterm birth (<37 weeks)4.3 (58 828)4.1 (47 775)4.3 (2040)5.4 (9013)
 Low/High birth weight% (count)% (count)% (count)% (count)
 Low birth weight (<2500 g)3.0 (40 006)2.7 (30 443)3.0 (1387)5.0 (8176)
 High birth weight (>4500 g)3.1 (41 054)3.3 (37 165)2.8 (1313)1.6 (2576)
 Small for gestational age (<10th percentile)% (count)% (count)% (count)% (count)
 Weight11.5 (158 817)10.4 (120 800)13.6 (6483)19.1 (31 534)
 Body length6.0 (81 869)5.2 (60 003)7.0 (3345)11.2 (18 521)
 Head circumference (cm)*10.9 (69 350)10.1 (54 321)13.3 (4675)16.4 (10 354)
 Abnormal body proportions% (count)% (count)% (count)% (count)
 High ponderal index11.0 (136 918)11.1 (116 902)11.8 (5111)10.1 (14 905)
 Low brain-to-body ratio*11.1 (63 520)11.2 (54 554)12.5 (3968)9.2 (4998)
 High head-to-length ratio*9.6 (60 358)9.8 (49 830)8.9 (3560)8.3 (6960)
  • *Available since 1 January 2004.