UCHealth Ask an Expert: Advanced Maternal Age

We are so thankful to UCHealth maternal-fetal medicine specialist Laura Klein, MD, for taking time to answer our important questions submitted by our community of moms regarding advanced maternal age.
Ask an Expert

For many years, the medical profession has considered women older than age 35 to be higher risk when it comes to pregnancy. Although many women age 40 and older are now having successful pregnancies, that standard remains.

“But pregnancy after age 35 is certainly not an untenable situation,” said Dr. Laura Klein, medical director of Maternal-Fetal Medicine at UCHealth Memorial Hospital and of the Memorial Star High Risk Obstetric transport team, which brings patients from throughout Southern Colorado to Memorial to receive the specialized care they need.

Asked about advanced maternal age pregnancies, Klein had a lot of good insight and advice.

“We define advanced maternal age as women aged 35 or older.  This is an arbitrary cutoff as the risks increase incrementally with advancing age, but is useful in clinical practice.  The risks associated with being advanced maternal age generally fall into two categories: genetic risks and medical risks.”

Dr. Klein answered questions on advanced maternal age sent in by our readers – some questions have been grouped together because of similarity.

Q: What are the special considerations to keep in mind for women 35 years and older? (what risks are there and what % chance it would happen in an otherwise normal pregnancy)

Q: Why are women over 35 considered “high risk”? Does this apply to all healthy women also? What additional testing/follow ups are require for pregnancies in women over 35?

Q: What changes in women when they turn 35 that creates cause for concern and greater monitoring throughout pregnancy?

A: We define “advanced maternal age” or “AMA” as women aged 35 or older. This is an arbitrary cutoff as the risks increase incrementally with advancing age, but is useful in clinical practice.  The risks associated with being AMA generally fall into 2 categories: (1) Genetic risks and (2) Medical risks.

Genetic risks
All of a woman’s eggs are present when she is born. Therefore, with aging of the eggs during the course of her life, the risk for errors in chromosome number gradually increases with advancing maternal age.

The most common chromosome abnormalities are Down syndrome (Trisomy 21), Trisomy 18 and Trisomy 13. Trisomy means having three copies of one chromosome rather than the normal two copies.  These conditions occur randomly and can happen in pregnant women of any age, but statistically they become much more common after age 35. The risk for having a baby with Down syndrome (measured during the second trimester of pregnancy) is approximately 1/1000 in a 25-year-old woman, 1/250 in a 35-year-old woman, 1/69 in a 40-year-old woman, and 1/19 in a 45-year-old woman.  

Although the increase in risk is dramatic, you can see that the absolute risk for a 35-year-old woman to have a baby with Down syndrome remains less than 1 percent.  Unfortunately, the risk for having a baby with a chromosome abnormality is dependent only on the mother’s age and cannot be improved with a healthy lifestyle.

There are currently many ways to test for chromosome problems during pregnancy, with traditional invasive tests (amniocentesis or chorionic villus sampling) and newer non-invasive screening tests (including cell-free fetal DNA analysis, ultrasound, and biochemical tests).

We recommend meeting with a maternal-fetal medicine specialist and/or genetic counselor during the first trimester to discuss these options. A detailed fetal anatomy ultrasound is also recommended in the  second trimester to screen for birth defects.

Medical risks
As women age, they are more likely to develop chronic medical problems such as diabetes, chronic hypertension, obesity, etc.  These chronic conditions can dramatically increase the risk for problems during pregnancy. If you have chronic medical problems and are considering pregnancy, talk to your OB/Gyn provider and they may consider referring you for a preconception consultation with a maternal-fetal medicine (high-risk pregnancy) specialist. For diabetes in particular, working on managing the disease prior to pregnancy can really improve the chance of having a healthy baby.

Women who are over 35 but are in good health without chronic medical problems often have uneventful pregnancies.

Q: What extra actions should I take (diet, supplements, blood tests etc) before trying for a baby after 35?

A: Before pregnancy, the most basic things are really the most important. All women attempting to conceive should take a daily prenatal vitamin containing 400 mcg of folic acid, ideally for three months prior to conception. If you take medications, schedule a preconception visit with your OB/Gyn provider to review which medications should be stopped before pregnancy. Don’t smoke cigarettes, use marijuana or illicit drugs. Alcohol should be avoided completely after a positive pregnancy test or whenever you think you might be pregnant.

Q: Are we “over 35ers” likely to experience greater fatigue and/or morning sickness?

A: No, these symptoms are extremely variable between pregnant women but really do not correlate with age.

Q: Are prenatal visits required earlier for women over 35? If so, when and why?

A: If you are feeling well, the first prenatal visit is normally scheduled at around 8-10 weeks of gestation and there is no need to be seen earlier.  For women over 35, prenatal care should be established by approximately 10-12 weeks of gestation so that you have the full range of options available for genetic testing.  Women over 35 are at higher risk for miscarriage, so if you have abnormal symptoms during the first trimester such as vaginal bleeding (more than spotting) or severe cramping, call your OB provider to schedule an earlier appointment.

Q: Everyone always focuses on the risks of a geriatric pregnancy. In your opinion (medical or otherwise) are there any benefits?

A: Absolutely.  For some women, being over 35 means that they have had time to develop the maturity and resources to be great parents.

Q: What can I do for myself before I turn 35 to reduce pregnancy risks and birth defects associated with advanced maternal age? How common are chromosomal abnormalities and birth defects? How often have you seen in your practice?

A: Keep in mind that you may have more difficulty conceiving after age 35.  The chance of having trouble conceiving appears to be less than 10 percent in women under 35, versus approximately 33 percent in women aged 35-39, and 50 percent in women over 40.  For women under 35 we recommend trying to conceive for one year, and then considering testing and treatment for infertility.  For women over 35 you may consider evaluation by an OB/Gyn physician or reproductive endocrinologist if you are unable to conceive within six months.    

As already noted, chromosome abnormalities are more common in women 35 and older. Certain birth defects, such as congenital heart defects, may also be more common in women 35 and older. Therefore we recommend a second trimester detailed fetal anatomy survey, typically done in a maternal-fetal medicine (MFM) office, rather than the standard OB fetal anatomy survey performed in a low-risk pregnancy.

Q: I have heard women in their late thirties are more likely to have twins and triplets. Is this a fact? If so, why is that and what additional risks does this pose?

A: Yes, women who are 35 and older are at increased risk for multiple pregnancies. This occurs primarily for two reasons:

First, women aged 35 and older have a higher chance of ovulating two eggs during the same menstrual cycle, which causes dizygotic (fraternal) twins.  However, the majority of spontaneous pregnancies in women over 35 are still singletons.

Second, women aged 35 and older are more likely to use fertility treatments, which can increase the risk for both dizygotic (fraternal) and monozygotic (identical) twins, as well as triplets and higher.

Having a multiple pregnancy dramatically increases the risk for pregnancy problems, including miscarriage, birth defects, premature birth, preeclampsia, gestational diabetes, low birth weight, and stillbirth.  Multiple pregnancies are often managed by a maternal-fetal medicine specialist in conjunction with your primary OB provider.

Q: I am in my 40s. My doctor said I will have to be induced early due to risks of carrying to term. What are the risks and do I have the option to refuse induction?

A: The risk for stillbirth – death of the baby prior to delivery –  is a little bit higher in women 35 and older, but this is fortunately still a rare complication. The increased risk for stillbirth in women over age 35 mainly occurs late in pregnancy, after 38 weeks of gestation (the due date is 40 weeks of gestation).  The risk for having a stillbirth at full term (37-41 weeks of gestation) appears to be 1 in 382 for women age 35-39, and 1 in 267 for women 40 or older.  Compared with a woman under 35, the risk for stillbirth at full term is approximately 30 percent higher in women age 35-39 and 80-90 percent higher in women 40 or older.  

There are a couple of things that we recommend to try to reduce this risk:
  1.   Fetal testing during the last few weeks of pregnancy, with non-stress tests (NST’s) and/or biophysical profiles (BPP’s).  These tests are designed to determine whether a baby is getting enough oxygen, and if there are concerning signs, early delivery could be considered.

  1.   Planned delivery at 39-40 weeks.  If your due date has been firmly established by an early ultrasound (before 20 weeks of gestation) then we can be confident that the baby is fully mature at 39 weeks.  Delivery at 39-40 weeks will prevent stillbirths after 40 weeks.

Induction at 39-40 weeks is something that you should discuss with your OB provider, but it is ultimately your decision.  Some women prefer to accept the small risk of stillbirth in order to wait for natural labor.

Q: If I’ve had normal, healthy pregnancies in my twenties, is there a greater chance that I’d have the same for a pregnancy after 35, or is it just a whole new world at that point?

A: The risk for having a baby with a chromosome abnormality is significantly higher after age 35.  However, the fact that you have had prior normal healthy pregnancies reduces the risk for complications such as premature delivery and preeclampsia.

Q: I went through about two years or unsuccessful fertility treatments and became pregnant naturally with my first child at age 35 a month after the third unsuccessful ITI attempt and after stopping all fertility treatments. I’m not 38 and we’ve been trying for a second child the last nine months. Given my advanced maternal age and despite the lack of success using fertility treatment before, should we be pursuing fertility treatment to become pregnant again?

A: Yes, since you are now over age 35 and have been trying to conceive for greater than 6 months, it would be appropriate to pursue fertility treatment.

Q: What is the risk of miscarriage for women age 35 and older? Can you break down the numbers? Why is there are greater risk?

A: Miscarriages are common and can occur in women of any age.  However, the risk is significantly greater in women 35 and older.  One study estimated that the risk for miscarriage in women aged 25-29 was 12%, versus 25% at age 35-39 and 51% at age 40-44.  The extra miscarriages most often are caused by embryos with chromosome abnormalities.

Q: I am currently in my late 20s but would love to have a large family. Given my timeline (or lack of) prior to turning 35, do you ever recommend freezing eggs? Does this prevent eggs “getting old” and reduce future risks? Or is carrying a baby at age 35 and older still risky regardless?

A: Freezing eggs prior to age 35 will reduce the genetic risks if these eggs are used to conceive after age 35.  The medical risks described above are not affected by egg freezing.

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About Laura Klein, MD


Dr. Laura Klein is the medical director of Maternal-Fetal Medicine at UCHealth Memorial Hospital. Dr. Klein also serves as the medical director of the Memorial Star High Risk Obstetric transport team, which brings pregnant patients from throughout Southern Colorado to Memorial in order to receive the specialized care that they need. She is board-certified in Obstetrics & Gynecology and Maternal-Fetal Medicine. Dr. Klein graduated from the University of Colorado Health Sciences Center School of Medicine, and also completed her residency in Obstetrics and Gynecology and fellowship in Maternal-Fetal Medicine at the University of Colorado Health Sciences Center. Klein grew up in the Colorado Springs area and has been practicing at UCHealth Memorial Hospital since 2006. As a maternal-fetal medicine specialist, she cares for high-risk pregnant women and their infants. “I always keep in mind that I have two patients (or sometimes 3 or 4 in the case of a twin or triplet pregnancy!) I am honored to work with pregnant patients and their families during such an important time in their lives. Many of my patients face significant challenges during pregnancy, and I enjoy developing a plan of care with the goal of giving them the best possible outcome for both mother and baby,” she said. One of her areas of expertise is in prenatal diagnosis, including specialized fetal ultrasound with 3D and 4D, fetal echocardiography, amniocentesis and chorionic villus sampling. She said, “It is amazing that we are able to discover so much information about the health and development of an infant even before birth, and this information is critical in order to improve the health of the mother and baby.”  Klein’s personal interests include skiing, trail running, and spending time with her husband and three children.