Advanced Maternal Age: Risks & Recommendations
Welcome back to another episode of the OB/GYN Resident Survival Guide. Before we jump in, I want to remind you about a free resource I created last year called the OB/GYN Residency Starter Pack. It’s a short PDF with tips and links to help you freshen up your skills before day one of residency. I know Match Day is still a few months away, but I also know many of you still have sub-I’s to complete—or you’re just trying to manifest for the match! I realized this week that over 1,000 people have downloaded it, so if you haven’t checked it out yet, go take a look.
Now, let’s get into today’s topic: advanced maternal age.
What is Advanced Maternal Age?
Advanced maternal age (AMA) is defined as maternal age 35 years or older at the time of delivery. That means if a 34-year-old patient comes in for a new OB visit, but her birthday will occur before delivery (or before her estimated due date), she still falls into the AMA category.
So why is this topic relevant?
The average maternal age has been rising globally since around the year 2000, and by 2020, about 19% of pregnancies in the United States occurred in women aged 35 years or older. As obstetric providers, we are routinely caring for patients in this age group—which means we need to understand what risks are relevant, how to counsel these patients, and what interventions can be offered to help optimize outcomes.
This is also important because there is evidence suggesting that disparities in morbidity and mortality are greater in the AMA population when compared with younger maternal age groups. Patients deserve clear counseling about how age may impact pregnancy, and what steps can be taken to improve outcomes.
Risks of Advanced Maternal Age: Maternal vs. Fetal
When talking about AMA, it’s helpful to break risks into two categories: maternal risks and fetal risks.
Maternal Risks
For the mother, being AMA increases the risk of developing:
Gestational diabetes
Gestational hypertension
Preeclampsia
Postpartum hemorrhage
Labor dysfunction
Cesarean delivery
AMA patients are also more likely to experience multiple gestation pregnancies, such as twins. This is likely related to increased use of assisted reproductive technology (ART) in this age group.
Fetal Risks
For the fetus, AMA is associated with increased risk of:
Spontaneous abortion
Intrauterine fetal demise
Congenital anomalies
Chromosomal abnormalities
Abnormal fetal growth
Preterm birth
Low birth weight
A key point: most of these outcomes become more likely with increasing maternal age. For example, the risk of having a genetically abnormal fetus at age 50 is much higher than at age 35.
Counseling and Management: What Can We Actually Do?
One of the best opportunities to discuss AMA is before pregnancy, during preconception counseling. This may happen when a patient comes in for their annual gynecology exam, routine follow-up, or even contraception counseling. These visits are a great time to ask whether they plan to conceive in the near future—and to assess not just age, but also other comorbidities that could affect pregnancy.
Unfortunately, age itself isn’t modifiable. You can counsel younger patients that delaying pregnancy may increase fertility challenges and pregnancy risk—but if someone is 37 and wants to get pregnant now, they can’t rewind the clock.
So what can we do?
Inform patients of the risks associated with AMA
Identify modifiable risk factors—and optimize them
This includes addressing conditions like obesity, diabetes, and hypertension, and encouraging lifestyle changes that improve baseline health before conception. Sometimes, depending on severity of comorbidities, there may also be conversations about how pregnancy may not be advisable due to compounding risk factors.
Management Once the Patient is Pregnant
The next major counseling opportunity is the new OB visit. If a patient is already pregnant and is 35 or older, it becomes important to review how AMA may impact pregnancy and to discuss what interventions can potentially reduce risk.
For example:
Low-dose aspirin for preeclampsia prevention (if the patient has one or more moderate risk factors), ideally started between 12–16 weeks
Antenatal fetal surveillance, such as NSTs
Consideration of induction of labor at 39 weeks in patients expected to be 40 years or older at delivery
That said, the evidence supporting fetal surveillance and early induction isn’t the strongest. However, because there may be benefit, many institutions follow protocols based on MFM guidance.
Other recommended interventions for AMA patients often include routine standard pregnancy care as well, such as:
First trimester ultrasound
Detailed anatomy scan
Consideration of third trimester growth ultrasound
Offering genetic screening and diagnostic testing
Final Recap
Advanced maternal age is becoming more common, which means it’s more important than ever to understand the risks and how to counsel patients clearly and confidently. While age itself isn’t modifiable, we can identify other risk factors early, optimize health in the preconception and prenatal period, and offer evidence-based interventions that support safer pregnancies and better outcomes.
References
CDC Statistics
https://www.cdc.gov/nchs/data/nvsr/nvsr74/nvsr74-09.pdf
https://www.cdc.gov/nchs/fastats/births.htm
ACOG CC#11: Pregnancy at Age 35 Years or Older
Pregnancy-Related Mortality in the United States, 2011-2013
https://pubmed.ncbi.nlm.nih.gov/28697109/
Variation in relationships between maternal age at first birth and pregnancy outcomes by maternal race: a population-based cohort study in the United States
https://pubmed.ncbi.nlm.nih.gov/31843851/
Effect of maternal age on emergency cesarean section
https://pubmed.ncbi.nlm.nih.gov/30905245/
Aspirin Use to Prevent Preeclampsia and Related Morbidity and Mortality US Preventive Services Task Force Recommendation Statement
https://jamanetwork.com/journals/jama/fullarticle/2784499
Low-Dose Aspirin Use for the Prevention of Preeclampsia and Related Morbidity and Mortality
Stillbirth at term in women of advanced maternal age in the United States: when could the antenatal testing be initiated?
https://pubmed.ncbi.nlm.nih.gov/18437644/
Maternal age and the risk of stillbirth throughout pregnancy in the United States
https://pubmed.ncbi.nlm.nih.gov/16949411/
Landon, Mark B.; Galan, Henry L.; Jauniaux, Eric R. M.; Driscoll, Deborah A.; Berghella, Vincenzo; Grobman, William A.; Kilpatrick, Sarah J.; Cahill, Alison G.. Gabbe's Obstetrics: Normal and Problem Pregnancies (p. 547). (Function). Kindle Edition.
