[Assisted reproduction techniques and the health of the newborn]

The impact of delayed maternity on foetal growth in Spain: An assessment by population attributable fraction

BACKGROUND

Delayed childbearing is considered a risk factor for maternal-foetal health. As in other higher-income countries, in Spain age at maternity has steadily increased during the last two decades.

AIM

To quantify the impact of the delay in the age at maternity on small for gestational age (SGA) categories of <3rd, 3rd-5th and 5th-10th percentiles.

METHODS

2,672,350 singleton live births born to Spanish mothers in 2007-2015 were analysed. Adjusted relative risk was calculated to estimate the adjusted partial population attributable fractions (PAF_p) for mothers aged 35-39 and ≥40 years for each category of SGA considering the interaction between age at maternity and parity.

FINDINGS

Primipara 35-39 years old mothers have the highest PAF_p in the three categories of SGA, with the maximum value for SGA <3rd percentile (2.57%, 95% CI 2.25, 2.88). PAF_p for both primipara and multipara ≥40 years old mothers were less than 1%. PAF_p for primipara older mothers increased significantly in 2007-2015 for the three categories of SGA, more clearly among those aged 35-39 years. The contribution of multipara mothers of both age groups did not increase significantly during the period.

CONCLUSION

Delayed maternity is a significant adjusted risk factor for SGA, contributing to the increase of its prevalence. However, results also suggest a limited clinical impact of delayed maternity on foetal growth. Positive changes in maternal profile associated with the shift in maternal age might contribute to explain the limited impact of mothers aged 35 years and older on negative birth outcome in Spain.

Obstetric and perinatal outcomes in women ≥40years of age: Associations with fetal growth disorders

BACKGROUND

Evidence indicates that advanced maternal age is associated with adverse obstetric and perinatal outcomes. The purpose of this study was to evaluate pregnancy outcomes in women of advanced maternal age (≥40years).

METHODS

Using a prospective study design, data were collected by the Department of Obstetrics at the San Joan de Deu Hospital of Barcelona during the 1 June 2009 to 31 May 2012 period. The results were compared across three maternal age groups (≥40 [n=654], 35-39 [n=2781], and <35 [n=7893] years).

RESULTS

Of the 11328 births recorded during the study period, pregnancy-related complications were more common in women ≥40years of age. The most common disorder was diabetes (8.5% in the ≥40, 5.3% in the 35-39, and 3.0% in the <35years age groups). The women ≥40years of age also had significantly more premature births (p=0.001) and cesarean sections (17% in the ≥40, 12.5% in the 35-39, and 7.9% in the <35-year age groups; p=0.001). Intrauterine growth retardation was significantly more frequent in women aged ≥40years (17.4% in the ≥40, 15% in the 35-39, and 14.0% in the <35-year age groups; p=0.03). Fetal macrosomia was significantly more common in women ≥40years (15.4% in the ≥40, 12.6% in the 35-39, and 12% in the <35-year age groups; p=0.03).

CONCLUSION

Maternal age ≥40years was associated with poorer obstetric and perinatal outcomes and increased the risks of cesarean section, intrauterine growth retardation, and fetal macrosomia.