Background Immigration from low income countries represents a recent and increasing reality in Portugal. The legalisation process is slow and the illegal stay may represent a barrier to healthcare access. The objective of this study was to relate the illegal stay condition with the mother's obstetric surveillance.

Participants and Methods The sample included 499 immigrants living in Portugal, consecutively selected during the year 2010 in 21 Portuguese maternity hospitals. Data were collected in a face-to-face interview on the second day after delivery and with the consultation of medical hospital records. We considered adequate obstetric surveillance (AOS) if the mother had six or more appointments during pregnancy and the first occurred during the first trimester.

Results In this sample, the proportion of illegal immigrants was 10.7%. The prevalence of AOS was 73.5%, significantly lower in mothers in illegal situation (59.1% vs 77.9%, p<0.01). AOS was associated with maternal age (≤25 years=57.3%, 26–30 years=78.9%, >30 years=79.9%, p<0.01), women's education (<6 years=60.6%, 7–12 years=65.3% >12 years=90.9%, p<0.01), marital status (single/divorced=62.0%, married=79.9%, p<0.01), profession (white collar=84.5%, blue collar=68.3% p<0.01) wanted pregnancy (yes=81.4%, no=50.5%, p<0.01). After adjustment by non conditional logistic regression for mothers age, education and marital status, the illegal stay is associated with AOS (OR=0.48; 95% CI 0.29 to 0.82).

Conclusion Among immigrant pregnant women living in Portugal, the AOS is associated with illegal stay condition.