Advanced Maternal Age and Risk of Intrauterine Fetal Death

September 13, 2007

SMFM 27th Annual Meeting 2007

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read the abstract:  Advanced Maternal Age (AMA) Is An Independent Predictor Of Intrauterine Fetal Death At Term


Alix Boyle: Hi, this is Alix Boyle reporting for We are here at the SMFM meeting in San Francisco, 2007, and today we are speaking with Dr. Ozan Bahtiyar from Yale University. Tell us about your research.

Ozan Bahtiyar, MD: What we wanted to look at was we have a large data-set from the CDC and we wanted to investigate the effect of the advanced maternal age and its relation to intra-uterine fetal death. So we restricted our study to singleton gestations and we tried to limit our study as best we could by eliminating the fetuses with congenital abnormalities and mothers with medical problems in the past. So we ended up with approximately 6 million deliveries without any complications during their pregnancy. We looked at the intra-uterine fetal death rates in those mothers. We stratified the patients in five year age groups, between 15 and 44 years old, meaning 15 to 19, 20 to 24 and up to 44. Then we showed that there is a significant increase in the intra-uterine fetal death with advancing maternal age and that risk is almost three times higher in mothers age 40 and up. Then after this, we also attempted for the first time to show how much antenatal testing would be required to identify the pregnancies at risk. Our assumptions were that antenatal testing would find these patients at risk so that we would be able to decrease the risk of intra-uterine death to the baseline, which is the 25 to 29 years old group. We calculated that for mothers aged 40 and up, approximately 490 antenatal testing is required between 38 and 40 weeks gestation. The reason we chose to use the 38 weeks gestation is there are no clear indications or guidelines by the American College of OB/GYN regarding antenatal testing. They recommend testing for some medical conditions and abnormal past history; however, they uniformly recommend it and in practice in the United States, it is uniformly recommended that after 41 weeks of pregnancy, patients start to have antenatal testing. So when we looked at our data, we saw that the mothers aged 40 and higher at 38 weeks, their risk was equal to younger mothers at 41 weeks. The data spoke to itself that it was warranted to test the mothers starting from 38 weeks and up until term.

Alix Boyle: So those were your results, that you would test mothers earlier in pregnancy?

Ozan Bahtiyar, MD: Correct. Our results, again, showed that mothers aged between 40 and 44 are at a higher risk for intra-uterine fetal death. The risk is approximately three times higher than the baseline and their risk reaches to a very critical point earlier in gestation, approximately 38 weeks of gestation. The third result was that the number of tests needed was only 494 as compared to the 1,700 for mothers between 35 and 39 years old. So technically, it is possible to have this much testing in screening without any significant burden on the system.

Alix Boyle: What does this mean in the future for the treatment of older mothers?

Ozan Bahtiyar, MD: If a mother who is older than 40 years of age without any medical complications, they would normally have routine perinatal care. However, our data would put them in a slightly different place. What our data shows is that mothers who are of advanced maternal age should probably be monitored closely and the antenatal testing should be started earlier in pregnancy. However, this definitely does not take the place of perinatal visits and monitoring, things like that.

Alix Boyle: Okay. Thank you, Dr Bahtiyar.

Ozan Bahtiyar, MD: Thank you.