Intrauterine Growth Restriction (IUGR)

When a baby does not grow as expected during pregnancy, parents naturally feel worried and want clear information about what this means for their child’s health. Intrauterine growth restriction (IUGR) is one of the most common complications identified during prenatal care, and understanding it helps families prepare for the medical decisions and care that may follow.

This page explains what IUGR is, why it happens, how doctors monitor and manage it, and what families can expect for their baby’s health and development. Our goal is to provide accurate, compassionate information so you can make informed decisions and know what support is available.

Understanding Intrauterine Growth Restriction

Intrauterine growth restriction refers to a condition where a baby does not reach its expected size during pregnancy. Doctors diagnose IUGR when a fetus measures below the expected growth range for its gestational age, considering factors like sex and family background.

You may also hear the term “small for gestational age” or SGA. While these terms are sometimes used together, IUGR specifically describes a clinical situation where the baby shows signs of not getting adequate nutrition or oxygen in the womb, not just being constitutionally small. Some babies are naturally smaller due to genetics and grow perfectly healthy. IUGR, on the other hand, indicates an underlying problem affecting growth.

The distinction matters because babies with true IUGR face different risks and need closer monitoring than babies who are simply small but healthy.

Why IUGR Happens

Growth restriction occurs when something interferes with the baby’s ability to receive nutrients and oxygen through the placenta. The causes fall into three main categories.

Maternal Health Conditions

Several maternal factors can reduce blood flow to the placenta or affect the baby’s development:

• Chronic high blood pressure or preeclampsia
• Diabetes that is not well controlled
• Poor nutrition or severe malnutrition
• Smoking, alcohol use, or drug use during pregnancy
• Infections during pregnancy, including toxoplasmosis, rubella, cytomegalovirus, herpes simplex, HIV, and syphilis
• Very young maternal age (adolescent pregnancy)

Recent research has shown that maternal COVID-19 infection can increase the risk of pregnancy-related high blood pressure, which in turn raises the risk of IUGR.

Placental Problems

The placenta is the lifeline between mother and baby. When it does not develop properly or becomes damaged, the baby cannot receive adequate nourishment. Placental issues include:

• Poor placental development from the start of pregnancy
• Blood clots or areas of dead tissue in the placenta
• Placental infections
• Abnormal implantation or attachment

In developed countries, problems with placental blood flow caused by maternal high blood pressure and metabolic conditions are the most common reasons for IUGR.

Fetal Factors

Sometimes the growth restriction stems from the baby itself:

• Chromosomal abnormalities or genetic conditions
• Congenital malformations
• Multiple pregnancies (twins, triplets)
• Fetal infections

Each case is different, and doctors work to identify the specific cause through prenatal testing and ultrasound evaluations.

Recognizing and Diagnosing IUGR

Most cases of IUGR are identified during routine prenatal ultrasound examinations. Your healthcare provider may notice that the baby’s measurements are smaller than expected for the number of weeks you have been pregnant.

To confirm IUGR and assess its severity, doctors use several tools:

Ultrasound measurements track the baby’s head circumference, abdominal circumference, and limb lengths over time. Repeated scans help determine if growth has slowed or stopped.

Doppler studies use sound waves to measure blood flow through the umbilical cord and other vessels. Abnormal blood flow patterns suggest the placenta is not working well and the baby may be under stress.

Amniotic fluid levels are checked because low fluid can indicate the baby is not producing enough urine, a sign of poor nutrition.

Once a baby is born, doctors confirm IUGR if the birth weight falls below the 10th percentile for gestational age. These babies may show visible signs of malnutrition, including:

• A thin or wasted appearance with little body fat
• Loose, dry skin
• A disproportionately large head compared to the body (in some cases)

Immediate Health Concerns After Birth

Babies born with IUGR face several potential complications in the first days and weeks of life. Not every baby experiences all of these problems, but medical teams watch carefully for:

Low blood sugar (hypoglycemia) happens because these babies have limited energy stores. They need frequent feedings and blood sugar monitoring.

Difficulty maintaining body temperature (hypothermia) occurs because babies with IUGR have less body fat for insulation.

High red blood cell count (polycythemia) can develop as the baby’s body tries to compensate for low oxygen levels in the womb. This makes the blood thicker and harder to pump.

Trouble breathing or low oxygen at birth (perinatal asphyxia) may occur if the placenta was severely compromised.

Feeding difficulties are common because these babies may tire easily or have trouble coordinating sucking and swallowing.

Increased risk of infection exists because stressed babies may have weaker immune systems.

The neonatal care team addresses these concerns with close monitoring, temperature support, feeding assistance, and treatment as needed.

Medical Management During Pregnancy

Unfortunately, no treatment can directly reverse IUGR once it develops. Medical care focuses on supporting the mother’s health, monitoring the baby closely, and choosing the right time for delivery.

Increased Monitoring

When IUGR is suspected or confirmed, your prenatal visits become more frequent. You can expect:

• More ultrasounds to track growth and fluid levels
• Regular Doppler studies to assess blood flow
• Non-stress tests or biophysical profiles to check the baby’s well-being
• Closer attention to maternal blood pressure and overall health

This intensive monitoring helps doctors determine if the baby is tolerating the situation or if delivery should happen sooner.

Optimizing Maternal Health

Doctors work to address any treatable causes:

• Managing high blood pressure or preeclampsia
• Improving nutrition if that is a factor
• Treating infections
• Ensuring any chronic conditions like diabetes are well controlled
• Strongly encouraging cessation of smoking or substance use

For women at high risk of preeclampsia, taking low-dose aspirin starting in early pregnancy can reduce that risk and potentially prevent some cases of IUGR.

Timing Delivery

The most critical decision involves when to deliver the baby. Doctors balance two competing risks: the dangers of staying in a poorly functioning womb versus the complications of being born too early.

If monitoring shows the baby is in distress or no longer growing at all, early delivery may be necessary even if it means prematurity. Sometimes this requires induction of labor, and sometimes a cesarean section is safer.

In less severe cases, doctors aim to get as close to full term as possible while maintaining close surveillance.

Preventing IUGR

While not all cases can be prevented, several measures reduce risk:

• Maintaining good health before and during pregnancy, including proper nutrition
• Taking prenatal vitamins with adequate folic acid and multiple micronutrients
• Managing chronic conditions like high blood pressure and diabetes
• Avoiding smoking, alcohol, and recreational drugs
• Preventing infections through good hygiene and vaccinations
• Taking low-dose aspirin if your doctor recommends it for preeclampsia prevention

In some parts of the world, preventing malaria and using insecticide-treated bed nets significantly reduces IUGR rates. In the United States, addressing maternal nutrition and managing chronic diseases remain the most important prevention strategies.

Women with risk factors benefit from early prenatal care and discussions about optimizing health before conception when possible.

Long-Term Outlook

The effects of IUGR can extend beyond the newborn period. Parents should understand potential long-term health considerations, though not every child experiences these outcomes.

Childhood Development

Children who experienced significant IUGR have higher rates of:

• Developmental delays in motor skills, language, or learning
• Smaller stature or slower growth during childhood
• Behavioral or attention difficulties

Early developmental screening and intervention services make a meaningful difference. Many children catch up with appropriate support.

Adult Health Risks

Research has shown that babies who were growth restricted face increased risks later in life for:

• Cardiovascular disease
• High blood pressure
• Type 2 diabetes
• Metabolic syndrome

Scientists believe that when a fetus adapts to poor nutrition in the womb, these adaptations can create vulnerabilities that emerge decades later. This does not mean every child will develop these conditions, but awareness allows for preventive health measures.

Statistics and Current Research

IUGR remains the second leading cause of death around the time of birth, after prematurity. The two conditions often overlap, as many growth-restricted babies are delivered early.

Researchers continue working to improve diagnosis and treatment. Current areas of study include:

• Genetic and genomic testing to identify underlying causes earlier
• Better prediction tools to identify at-risk pregnancies
• Nutritional interventions that might support fetal growth
• Understanding the biological mechanisms linking IUGR to adult disease

Medical centers in New York and across the country participate in research aimed at improving outcomes for babies affected by IUGR.

Support and Resources for Families

Learning that your baby has IUGR brings anxiety and questions. You are not alone, and support is available.

Medical Support

Your healthcare team should provide:

• Clear explanations of your baby’s condition and monitoring plan
• Coordination between maternal-fetal medicine specialists and neonatologists
• Guidance on nutrition and health optimization
• Planning for delivery and immediate newborn care

Do not hesitate to ask questions or request clarification about anything you do not understand. You have the right to be fully informed.

After Birth

Once your baby is born, ongoing support includes:

• NICU care if needed for initial stabilization
• Feeding support from lactation consultants or feeding specialists
• Follow-up appointments to track growth and development
• Referrals to early intervention programs if developmental concerns arise

Developmental and Social Support

Children who experienced IUGR benefit from:

• Regular developmental screenings
• Early intervention services starting in infancy if delays are identified
• Coordination with pediatricians who understand the long-term implications
• Connection to parent support groups or counseling services

Many states, including New York, offer early intervention programs at no cost to families. These programs provide therapy and support services in your home for children under three who have developmental delays or disabilities.

Finding Information and Connections

Navigating IUGR and birth-related medical challenges requires reliable information. NYBirthInjury.com exists to provide families with trusted, medically accurate resources and help connect you with qualified medical specialists and support services.

State health departments, children’s hospitals with NICU follow-up clinics, and organizations focused on pregnancy and infant health offer additional resources and connections to other families who have been through similar experiences.

Looking Ahead

While an IUGR diagnosis brings uncertainty and concern, many babies do well with appropriate monitoring, timely delivery, and attentive newborn care. Understanding the condition, staying engaged with your medical team, and accessing support resources gives your child the best possible start.

Every family’s experience is different. Some babies catch up quickly and thrive. Others need more intensive support and monitoring. Whatever your situation, asking questions, seeking information, and connecting with knowledgeable professionals helps you advocate effectively for your child’s health.

You did not cause this condition, and you are doing the right thing by seeking to understand it. With good medical care and family support, most children affected by IUGR grow up to lead healthy, fulfilling lives.