Understanding Small Babies and Fetal Growth Restriction (FGR)

Highlights

• Most babies born with a lower than average birthweight are born healthy.
• Most babies born between 37 and 42 weeks of pregnancy weigh between 2.5kg and 4kg.
• Some babies with an estimated fetal weight smaller than the average may be affected by fetal growth restriction (FGR).
• Causes for fetal growth restriction include genetic conditions, health issues such as high blood pressure and diabetes, and smoking or drinking alcohol during pregnancy.
• If you notice a change in fetal movements at any stage during your pregnancy, seek urgent advice from your doctor or midwife.

In This Article

• Understanding the Causes of Small Babies
• What is Small for Gestational Age (SGA)?
• What is Fetal Growth Restriction (FGR)?
• Factors that Increase the Risk of FGR
• Measuring Your Baby’s Growth
• Should I Be Concerned About My Baby’s Size?
• Birth Options for Babies with Low Birthweight
• Steps You Can Take to Minimize the Risk of a Small Baby
• What to Expect if Your Baby Is Born with Low Birthweight
• Key Questions to Ask Your Doctor
• Tools and Assistance

Understanding the Causes of Small Babies

Most babies born from 37 weeks of pregnancy weigh between 2.5 kg and 4 kg. However, some are born with a lower-than-average birth weight for their gestational age. This condition is known as being “small for gestational age” (SGA).

Many babies with a lower-than-average birth weight are born healthy. Some are small due to the size of their parents or genetic factors. In other cases, slow growth may be caused by fetal growth restriction (FGR).

What is Small for Gestational Age (SGA)?

SGA is a term used before birth or at birth to describe babies whose weight is below the 10th percentile for their sex and gestational age. Doctors can predict this based on pregnancy ultrasounds.

What is Fetal Growth Restriction (FGR)?

FGR occurs when a baby grows more slowly than expected during pregnancy. This means the baby is not reaching its full growth potential.

The most common reason for FGR is poor placenta development. When the placenta cannot provide enough nutrients and oxygen, the baby’s growth slows down. FGR increases the risk of pregnancy complications. Doctors may recommend closer monitoring if FGR is detected. This helps identify and address potential issues early.

Factors that Increase the Risk of FGR

Risk factors for FGR include:

• A history of small babies, pre-eclampsia, or stillbirth
• Infections that cross the placenta, such as cytomegalovirus (CMV)
• Chronic health conditions, including high blood pressure, kidney disease, or diabetes
• Severe anemia or malnutrition
• Smoking, alcohol consumption, or drug use
• Genetic or chromosomal conditions in the baby
• Multiple pregnancies (twins, triplets, or more)

Measuring Your Baby’s Growth

During routine prenatal check-ups, doctors or midwives use a tape measure to estimate the baby’s growth. They measure from the pubic bone to the top of the uterus (fundus). This is called the symphyseal fundal height (SFH) measurement.

If risk factors for FGR are present, doctors may monitor growth more closely with ultrasounds. Each pregnancy is unique. Doctors track the baby’s growth at every check-up. If growth slows, they discuss the next steps.

Should I Be Concerned About My Baby’s Size?

Most small babies are healthy. However, FGR increases the risk of complications, including stillbirth.

If a baby has FGR or is predicted to be SGA, doctors recommend regular ultrasounds and umbilical artery Doppler scans. Frequent monitoring helps reduce risks.

Attending all prenatal visits is crucial for monitoring the baby’s health. Keeping track of fetal movements is also important. Setting a daily reminder can help parents stay aware.

If the baby’s movements change, contacting a doctor or midwife immediately is essential.

Birth Options for Babies with Low Birthweight

If FGR is diagnosed, doctors may discuss early delivery options, such as inducing labor. Every case is different. Doctors provide guidance at every stage to support informed decisions.

Many babies with FGR can be delivered vaginally. However, additional care may be required during and after birth. It is best to give birth in a facility with access to specialized medical services.

Parents should discuss the best place for delivery with their doctor or midwife.

Steps You Can Take to Minimize the Risk of a Small Baby

In many cases, FGR cannot be prevented. However, maintaining good health during pregnancy can reduce risks. Recommended steps include:

• Avoiding smoking
• Eating a balanced, healthy diet
• Maintaining a healthy weight
• Avoiding alcohol and illegal drugs

What to Expect if Your Baby Is Born with Low Birthweight

Babies weighing less than 2.5 kg at birth may have proportionally larger heads. Some premature or low-birth-weight babies require monitoring in a neonatal intensive care unit (NICU) or a special care nursery (SCN). This stay may last a few hours, days, or longer, depending on the baby’s condition.

Low-birth-weight babies may face:

• Breathing or heart problems
• Low oxygen levels at birth
• Difficulty maintaining body temperature
• Feeding and weight gain issues
• Increased infection risk
• Vision or eye problems

These risks are higher for premature babies and those with FGR.

Most babies with low birth weight eventually catch up in growth. However, in later life, they may have an increased risk of:

• Heart problems
• Diabetes
• Obesity
• High blood pressure

Key Questions to Ask Your Doctor

Here are some questions to consider discussing with a healthcare provider:

• What does having a small baby mean for me and my baby’s health?
• Will I need more frequent check-ups? What will these include?
• How can I tell if my baby is doing well?
• Will having a small baby affect my delivery options?
• Could this impact future pregnancies?
• Will my baby need special care after birth?

Tools and Assistance

• Prenatal Check-Ups: Regular visits with your doctor or midwife help monitor growth and detect potential issues early.
• Ultrasound Monitoring: Frequent ultrasounds may be needed to track your baby’s growth and detect FGR or SGA.
• Umbilical Artery Doppler Scan: This test assesses blood flow to ensure your baby is getting enough nutrients and oxygen.
• Fetal Movement Tracking: Keep track of movements and contact your doctor if there are any changes.
• Specialized Care for Low Birthweight Babies: If needed, your baby may require care in a Neonatal Intensive Care Unit (NICU) or Special Care Nursery (SCN).
• Dietary and Lifestyle Support: A dietitian can help ensure proper nutrition during pregnancy, especially if complications arise.
• Mental Health Support: Seek counseling if you’re feeling stressed, anxious, or overwhelmed during pregnancy.
• Smoking, Alcohol, and Drug Support: Get help if you’re struggling with substance use during pregnancy.
• Birth Plan Guidance: Discuss early delivery or cesarean options with your doctor if necessary.
• Support Groups: Join groups for emotional support from others going through similar experiences.