Increase in Maternal Age and Impact on Pregnancy Outcomes

Introduction

Maternal age is the age of a mother at the time of delivery of her baby. There are three main categories for maternal age: young mothers, women in their 20s and advanced maternal age. The risks of pregnancy complications and poor delivery outcomes are known to increase with maternal age, while fertility declines. This article will shed light on the effects of the higher maternal age on pregnancy outcomes and ultimately on the mother and her baby.

Maternal age categories

There are three main maternal age categories.^1,2

• Young mothers, also known as adolescent mothers, are mothers who become pregnant and give birth between the ages of 11 and 19. Most pregnancies in this category are unplanned and are at risk of poor birth outcomes and developmental difficulties 

• Women in their 20s are known to be at their reproductive years' peak. Pregnancy is said to be physically easier for women in this category because there is a lower risk of diabetes and high blood pressure. Women are also less likely to have a miscarriage, gynaecological problems like uterine fibroids, babies born prematurely or with low birth weight or chromosomal disorders and are more likely to be fitter and healthier

• Advanced Maternal Age (AMA) has no standardised definition but is generally classified as 35 years or older. Maternal age of 40 years and above is classified as very advanced maternal age and above 45, as very late maternal age.³ AMA is known to be a major risk factor for adverse foetal and maternal outcomes. These include gestational hypertension (high blood pressure), gestational diabetes mellitus and caesarean delivery. Some of the fatal perinatal outcomes include pre-term labour, stillbirth, higher rates of chromosomal abnormalities and neonatal intensive care unit admissions

Potential impact of maternal age on pregnancy outcome

More women are now choosing to delay having children until later in their reproductive years. Several factors such as higher maternal education, fertility knowledge, use of modern contraceptives, age at first marriage and career objectives are significantly influencing this decision. More than ever, women are also taking charge of their reproductive health. Therefore, decisions about fertility and bearing children arise from individualism, self-realisation, personal development, and choice.

Delaying childbearing can be a challenge as increased maternal age has a major impact on a woman’s fertility and successful conception, both in assisted and natural reproduction. Fertility is known to be at its peak when women are in their 20s and starts to slowly decline when a woman is in her early 30s and faster after the age of 35. 

Women below 30 years of age have an 85% chance of conceiving within one year. At age 30, this drops to a 75% chance of conception. This declines further to 66% at the age of 35 and 44% at age 40.⁵ This can be attributed to the effect of ageing on the ovary and eggs.

As a woman ages, prenatal care becomes more important due to the increased risk for complications. Certain steps need to be taken to reduce these risks, including:

• Attending all prenatal screenings and appointments
• Regular exercise and a healthy diet
• Ensuring your preventive healthcare is up to date
• If any pre-existing medical conditions exist, ensure they are properly managed
• Daily usage of prenatal vitamins that include folic acid
• Zero alcohol consumption or tobacco products
• Getting enough rest and reducing stress levels
• Ensuring you gain a healthy amount of weight

After the age of 35, there is a higher risk of pregnancy-related complications which might increase the risk of miscarriage or stillbirth, lead to a C-section delivery or a higher risk of chromosomal conditions such as Down’s syndrome. Research shows that an increased incidence of miscarriage might be due to a decrease in the quality of eggs over time and an increased likelihood of chronic conditions such as high blood pressure or diabetes.

With higher maternal age comes an increase in the incidence of multiple pregnancies. The hormonal changes that occur in the body may cause the simultaneous release of more than one egg from the ovaries. 

Gestational diabetes is also more common in older mothers. When left untreated, it can cause the foetus to grow bigger than average, increasing the risk of injuries during childbirth or having a caesarean section. It can also increase the risk of preterm birth, high blood pressure and other complications for the infant.

Research also shows that an increased maternal age increases the risk of developing hypertension, also known as high blood pressure (HBP), in pregnancy. This requires close monitoring of both mother and baby throughout the pregnancy. To avoid complications, it is advised that mothers with HBP deliver their babies before the due date.⁵

Studies have shown that the incidences of preterm birth, congenital malformations, severe speech and language impairments (common in preterm babies), neonatal death, and intrauterine growth restriction (an important cause of foetal and neonatal morbidity and mortality) are higher among full-term newborns of mothers with advanced age.^6,7 The use of assisted reproductive technology has also been shown to be higher in women with advanced maternal age which might also increase the risks to the foetus and infant mentioned above. 

Mitigating risks and challenges

Although there is an elevated risk of having complications at an advanced maternal age, women should not be discouraged from having children, as studies have shown that many pregnancies have good outcomes. Instead, they should be advised to care for their health before conception. 

This should include taking folic acid supplements, stopping smoking and drinking alcohol, increasing physical activity and paying particular attention to achieving a healthy body weight. They should also be encouraged to perform tests that give information about the baby’s risk of a chromosome disorder like the aneuploidy screening tests as well as detailed ultrasound. Given the increased risk for stillbirth, AMA mothers should be offered labour induction or elective caesarean section at 39 weeks gestation.

Other ways of reducing the risks associated with AMA and pregnancy complications include:

• Self-education and a healthy lifestyle. This involves knowing the risks and preparing accordingly, improving your lifestyle, and engaging in healthy behaviours to protect yourself and your babies
• Receiving reassuring tests can offer relief from the fear of an increased risk of genetic problems in unborn babies
• Not dwelling on the risks to reduce anxiety and excessive stress and instead focusing on the positive aspects of AMA. This includes improved readiness, having a secure career and established relationship, emotional and personal maturity, and better problem-solving skills
• Communicating with healthcare professionals, ahead of and during pregnancy, to ensure proper monitoring and any symptoms or concerns are picked up immediately
• Religious beliefs and a sense of hope have been shown to help alleviate the fears of some AMA mothers and help them stay calm during pregnancy and child birth

Following these strategies can significantly reduce unfavourable outcomes in pregnancy for both mother and baby.

Summary

In the absence of other risk factors, pregnancy at AMA should generally be perceived as low risk. However, this category of women is prone to an increased incidence of several pregnancy complications, limited physical activity, risks associated with age, and previous poor reproductive history, thus increasing the incidence of unfavourable pregnancy outcomes and should therefore be well informed. 

These can be influenced by many factors including medical, physical, social, and personal reasons. Understanding the factors that influence pregnancy risks may help expectant mothers become informed and approach their healthcare providers to improve pregnancy outcomes through effective communication.