Monday, October 24, 2011

Briefcase or Diaper Bag: Decisions, Decisions

Understanding the risks of delaying childbirth: what every woman should know...

By J. Elaine Larmon, MD
Perinatologist, Perinatal Consulting Group


Many women are faced with this difficult decision: have a baby, or focus on their career. There are many factors that contribute to their decision on what time is the best time to have a baby.

In the past 25 years, older women in the United States have accounted for an increasing proportion of total births (14%). The mean age at the birth of a woman’s first child (around 25) has increased by 4 years since 1970.

The increased occurrence of births at an older maternal age is due to several factors including:
   • Number of women aged 35-45
   • The availability of reliable contraception
   • Wider opportunities for further education and career advancement for women

Maternal education is one of the strongest predictors for the use of contraception, timing of childbearing and total number of children. College-educated women tend to have higher first birthrates in the thirties, illustrating the trend of delayed child-bearing being related to educational achievement and career opportunities.

The Risks
Although many older couples tend to be more mature and financially stable, women who delay childbearing are at increased risk of infertility and pregnancy complications. Facts that women should know when planning the timing of their childbearing include:
   • The probability of achieving pregnancy begins to decline significantly at the age of 32
   • The incidence of coexisting medical disease and pregnancy complications also increase with advancing maternal age
   • Pregnancy complications that are increased include chromosomal abnormalities, some congenital anomalies, placenta previa, gestational diabetes, preeclampsia, cesarean delivery, ectopic pregnancy, miscarriages and stillbirths

Fertility
Advancing age is also associated with prolongation in the average time for achieving pregnancy. The probability of achieving a pregnancy in one menstrual cycle (fecundability) begins to decline significantly at about the age 32 with a more rapid decline around the age of 37. Sub-fertility is primarily related to the poor quality of aging eggs, decreased ovarian reserve (fewer eggs), and an altered hormonal environment resulting in ovulatory dysfunction.

Older women also have had more time to acquire medical and surgical conditions such as endometriosis, pelvic infection, endometrial polyps and fibroids, which can impair fertility. Lifestyle factors may also play a role. Older women may have a decreased frequency of sexual intercourse and are more likely to be obese.

Pregnancy Complications

1. Pregnancy Loss
    a. Miscarriage: Older women experience an increased rate of spontaneous miscarriage. These losses are both chromosomally abnormal and normal and primarily result from a decline in egg quality. Changes in the uterine environment and hormonal function may also play at role.

In a large series of studies from Scandinavia, the overall rate of miscarriages treated in hospitals was 11%. Assuming that only 80% of women with miscarriages were treated in the hospital setting, the risk for miscarriage in various age groups was calculated. The risk of miscarriage in women less 30 years was 12%, between 30-34 years it was 15%, between 35-39 years it was 25%, between 40-44 years it was 51% and at ages 45 and greater it was 93%.

    b. Ectopic Pregnancy: A maternal age of 35 or older is associated with a 4- to 8-fold increase in ectopic pregnancies. This is likely due to an accumulation of risk factors over time, such as multiple sexual partners, pelvic infection and tubal pathology.

    c. Stillbirths: Women 35 years old and older have a higher risk for stillbirths compared to younger women. The risk of stillbirth also increases with advancing gestational age and is most notable after 37 weeks. The increase in mortality is largely unexplained. The absolute risk of stillbirths in developed countries such as the United States is still small.

2. Co-existing Medical Conditions: The prevalence of medical and surgical illnesses such as cancer, hypertension, diabetes, renal disease, and autoimmune disease increase with advancing age.
    a. Hypertension: This is the most common medical problem encountered in pregnancy and is more prevalent in older women. The incidence of chronic hypertension is 4-fold higher in women 35 years old and older than in women 30-34 years of age. The incidence of preeclampsia in the general population is 3-4%, which increases to 5-15% in women greater than 40, and to 35% in women older than 50.

    b. Diabetes: Prevalence of this condition also increases with age. The incidence of both pre-existing and gestational diabetes increases 3- to 6-fold in women older than 40, compared to those 20-29 years old. Gestational diabetes occurs in the general population at rate of 3%, rising to 7-12% in women greater than 40 years of age and to 20% in women over 50. Pre-existing diabetes is associated with increased risks of structural birth defects and pregnancy loss.

3. Fetal Abnormalities
    a. Chromosomal Abnormalities: Analysis from spontaneous miscarriages, terminations, genetic amniocentesis, stillborn and live born infants show a steady increase in the risk of chromosomal abnormalities as a woman ages.

    b. Congenital Birth Defects: The risk of having a child with a congenital malformation may increase with age. Several but not all reports suggest that as a woman ages, the risk of non-chromosomal anomalies increases. In particular, heart defects seem to increase with advancing maternal age.

4.  Placental Problems: The prevalence of placental abruption and placenta previa is higher among older women.

5.  Multiple Gestation: Advancing age is associated with an increased prevalence of twin pregnancy which is due to a higher incidence of naturally conceived twins along with a higher use of artificial reproductive technology in older women.

In summary, women who delay childbearing are at increased risk of infertility and certain pregnancy complications. Knowledge of these obstetrical risks associated with advanced maternal age can help a woman make an informed decision about timing of childbearing. These risks should be balanced against career and personal issues that might favor delaying childbearing.

Dr. J. Elaine Larmon, MD is a Perinatologist at Perinatal Consulting Group, 3913 W. Prospect Avenue, Suite 102, Appleton, WI 54914. Contact Dr. Larmon at 920-729-7121 or meet her here.

About the Perinatal Consulting GroupThe caring team at the Perinatal Consulting Group provides specialty care to women with delicate pregnancies. We are focused on diagnosing, treating and caring for women and unborn babies who are at risk for complications or illness during pregnancy or who have been diagnosed with a disease or other medical problem. We work with your doctor to provide you and your baby with the special care you need. We are strictly a consultative practice, which means we do not perform primary care services. Patients receive a formal referral from their primary care provider and we work in conjunction with that provider (obstetrician, family practicioner or midwife) to ensure that you and your unborn baby get the best care possible. Learn more at www.perinatalconsultinggroup.com.