Advanced Maternal Age
Why 35?
Although a bit arbitrary, the age of 35 was initially chosen because of the similarity between the risk for having a baby with a chromosomal abnormality and the risk for miscarriage from an amniocentesis. No longer is age used as a sole indication for recommending genetic testing (i.e. Chorionic Villous Sampling "CVS" or Amniocentesis)—instead we leave this up to each individual patient. However, there are additional risks besides genetics alone.
What are the risks?
The risks during pregnancy increase with age, and these include operative delivery (forceps, vacuum, and cesarean delivery), preeclampsia (hypertension with protein in the urine), diabetes, stillbirth, preterm delivery, genetic abnormalities, and abnormal placental function.
What makes advanced maternal age risky?
This is such a difficult question that the answer should prefaced with, "Some mechanisms are just not known." With that said, we are seeing more complications with older moms than younger ones.
The genetic risk is probably understood the most because of our great advances in the understanding of the biology of conception. Each prospective mother is born with all the eggs she'll need for her entire life, leaving each egg in a state of hibernation until its release during an ovulatory cycle. Ovulating at age 14 vs. 48 results in two completely different risks because those eggs were produced at the same time in fetal life. The risk for Down Syndrome increases from 1/1,600 to 1/25 between puberty and menopause because as the egg continues to age, it becomes more vulnerable to a mistake during the process of ovulation.
Medical complications like hypertension and diabetes increase with age, and pregnancy is no different. Pregnancy-specific complications, such as preeclampsia and gestational diabetes, have not only a predilection for family history, but also an association with abnormal placental function that seems to worsen with maternal age. The enigma of increased stillbirth risk still has doctors scratching their heads, but the placental function is probably a big factor with this problem too.
Doctors are seeing an increasing number of women with cervical weakening, and this predisposes them to delivery in the third trimester, and in some cases before the baby is even viable (24 weeks). Many women with cervical weakening fly under the radar due to the subtleness of the signs and symptoms in early pregnancy. The cervix can begin shortening for a list of reasons as long as this article, so figuring out the actual cause is a key for any recommended treatment regimen. Whether it's a change in the cervical makeup with age, or damage with age, is not completely known, but it is likely a combination of the two with a dash of genetics thrown in.
What can you do to make advanced maternal age safer?
The genetic issue is becoming more and more complicated as our technology advances. No longer is a simple chromosomal analysis the answer … now we're moving into Microarray. Doctors are able to look at more of the fine details of your baby's genetic material, and in the future, this will probably be the first genetic test done, not the simple chromosomal evaluation. Most parents are choosing to pursue the genetic screening first, but that's your choice. Some go straight to genetic testing, regardless of age or risk because they just want to know.
The first trimester screen includes an evaluation of the fluid behind your baby's neck by ultrasound, the nasal bone assessment, blood flow evaluation, and some even measure the forehead angle. This is then combined with a finger-stick of the mom for blood analysis for a 95-96% detection of Down Syndrome. Your individual risk will be back within a week and many parents use this to decide what to do next. The genetic ultrasound is best performed between 19-20 weeks, a non-invasive way to evaluate your baby's anatomy and to search for chromosomal markers.
A genetic test is invasive, so there is a risk to the pregnancy. The risk for miscarriage is between 1/350 to 1/500 for amniocentesis and about 1/350 for CVS (placental sampling). The difference is timing for each procedure. CVS is done between 11-14 weeks and amniocentesis is done after 16 weeks. Genetic testing is considered the "Gold Standard" and definitive for chromosomal abnormalities like Down Syndrome.
What does prenatal care do?
Every prenatal visit includes blood pressure assessment and urine protein analysis to detect preeclampsia. Unfortunately, there is no treatment or prevention of preeclampsia at this time, but knowing is extremely important. The only cure is delivery, but not managing preeclampsia correctly is a major risk to the mom and baby.
Diabetes is usually tested for with a one-hour glucose challenge between 24-28 weeks of pregnancy. This screen is successful in detecting the majority of women developing gestational diabetes. Only 15% of women have to take a confirmatory 3-hour glucose challenge, and only 15% of those women require a special diet. Gestational diabetes is easy to control, and most women are successful with diet or the occasional use of an oral medicine to help normalize glucose levels.
Placental function and stillbirth are often grouped together. Evaluating your baby's growth between 28-30 weeks provides insight into placental function. Normally, a fetal testing regimen is begun at 34 weeks, a non-invasive way to confirm the well being of your baby. This will reduce the risk for stillbirth from 12/1,000 to less than 1/1,000, depending on the testing regimen chosen.
Most women have a wonderful pregnancy despite age, but being empowered with knowledge should help you feel more secure with your decisions.