Results
The participants were on average 29.1 (SD: 5.3) years old. The first antenatal care visit was on average at 12.9 (SD: 3.7) weeks, and 81.4% of the participants started antenatal care in the first 14 weeks of pregnancy. The pregnancy was on average recognized at 5.4 (SD: 2.3) weeks, and 81.7% of the participants recognized their pregnancy within 6 weeks. The participants who had their first antenatal visit within 14 weeks of pregnancy significantly differed in all studied predictors from participants who had their first antenatal visit later than 14 weeks, except for mental illness. Table 1 shows a detailed description of the study population.
Participants who recognized their pregnancy within 6 weeks had their first visit in antenatal care 1.25 weeks earlier (95% CI=-1.60; -0.91) than those who recognized their pregnancy later than 6 weeks (βadjusted=-0.63; 95% CI=-0.97; -0.28). In addition, all predictors were significantly associated with timing of antenatal care initiation (Table 2). The associations were most prominent for the following predictors: participants aged <20 years were 2.95 (95% CI=2.31; 3.63) weeks later than those aged 30-35 years; first generation migrants were 1.53 (95% CI=1.29; 1.78) weeks later than those without migration background; those with unplanned pregnancy and ambivalent feelings were 2.14 (95% CI=1.75; 2.54) weeks later than those with planned pregnancy; participants without sufficient Dutch language skills were 1.63 (95% CI= 1.25; 2.02) weeks later than those with sufficient Dutch language skills; those who already had 3 children or more were 1.57 (95% CI=0.90; 2.29) weeks later than nulliparous participants; participants with lower educational attainment were 1.50 (95% CI= 1.20; 1.81) weeks later than participants with higher educational attainment; unemployed participants were 1.60 (95% CI=1.35; 1.86) later than employed participants; those with a lower household income were 2.05 (95% CI=1.77; 2.34) weeks later than those with a higher household income; and those living in highly deprived neighborhoods were 1.52 (95% CI=1.24; 1.79) weeks later than those living in low deprived neighborhoods.
Hypothetically intervening on pregnancy recognition (≤6 weeks) reduced the inequalities in antenatal care initiation. These reductions were significant for age, migration background, pregnancy intention, education, employment, household income, housing, and neighborhood deprivation. Table 2 and Figure 1 show the inequality before and after the intervention, and the corresponding reductions. For example, the inequality between those aged <20 years and those aged 30-35 years was β=2.95 weeks (95% CI=2.31; 3.63) prior to the intervention, which became β=2.55 weeks (95% CI=1.91; 3.23) after the intervention, indicating a significant reduction of β=-0.40 (95% CI=-0.69; -0.15). Similarly, the inequality between those with unplanned and ambivalent pregnancy and those with planned pregnancy was β=2.14 weeks (95% CI=1.75; 2.54) prior to the intervention, which became β=1.77 weeks (95% CI=1.38; 2.18) after the intervention, indicating a significant reduction of β=-0.37 (95% CI=-0.57; -0.18).
Sensitivity analyses including only participants with a regular cycle (n=2360) are shown in Table S1. Participants who recognized their pregnancy within 6 weeks had their first visit in antenatal care 1.14 weeks (95%CI -1.58; -0.69) earlier than those who recognized their pregnancy after 6 weeks (βadjusted=-0.47, 95%CI -0.91; -0.03). All predictors remained associated with timing of antenatal care initiation. Hypothetically intervening on pregnancy recognition significantly reduced the inequalities for pregnancy intention (planned vs unplanned and ambivalent), migration background (no vs first generation), and neighborhood deprivation (low vs high).