Thyroid Dysfunction During Pregnancy: Impact on Infant Intelligence and Growth

Hypothyroidism? Low intelligence?

I would like to ask the doctor: I gave birth to my first son on January 31 last year, and when he was about 5 months old, I became pregnant again (while breastfeeding).
At that time, I had a cold shortly after becoming pregnant, and soon after, my neck swelled up.
After examination, I was diagnosed with hypothyroidism.
Initially, when I started taking thyroid hormone, I occasionally skipped the medication because I listened to my mother, who said that taking medication would be bad for the baby.
However, I later took the medication regularly for about 4 to 5 months until my thyroid was no longer swollen, and I stopped taking it on my own for about 3 months.
Later, when I was about 7 to 8 months pregnant, I read online that untreated maternal hypothyroidism could lead to issues with fetal intelligence, cretinism, growth retardation, preterm birth, and miscarriage, which scared me, so I went for blood tests and resumed medication (the blood test still showed hypothyroidism, and the doctor said it was impressive that I had not miscarried given my large belly).
I have been taking the medication since then, and this baby was born on February 12 this year.
The newborn's thyroid function test was normal.
However, I am still very worried and would like to ask the doctor:
1.
I did not take medication for about 3 months during the second trimester; could this period affect the baby's intelligence? However, during all prenatal check-ups before birth, the gynecologist said the baby's growth was normal and there should be no issues.
Is he correct?
2.
My due date was March 1, but I gave birth early on February 12, at about 37 weeks.
The baby was born weighing 3100 grams, measuring 51 cm in length, and had a head and chest circumference of 32 cm.
The doctor checked for any signs of distress or feeding issues, and everything was normal; the baby was not smaller than average.
Does this mean that the risk of cretinism due to my condition can be ruled out? Even if there is no cretinism, could my baby's intelligence still be affected and lower than average due to my situation?
3.
My husband says that babies with intelligence or brain issues usually show signs of growth retardation or other abnormalities (such as feeding or sleeping issues).
Is this true? However, at 1 month and 18 days, my baby weighed 5600 grams (75-90th percentile), measured 56.5 cm (50-75th percentile), and had a head circumference of 37.5 cm (25-50th percentile).
The doctor said he is growing very well, taller and heavier than my first son at the same age, and all other developments are normal.
Additionally, the brain ultrasound results at birth were also normal.
What is the likelihood of him having cretinism or cognitive deficits? He should be normal, right?
4.
He is now almost 2 months old and can turn his head towards the source of sound or objects, and he smiles when I play with him.
When placed on his stomach, he can slightly lift his head off the surface.
Given this developmental progress, his intelligence should be fine, right?
5.
If his intelligence is indeed affected by my situation, would extended breastfeeding help compensate for that?
6.
Are there any methods available at large hospitals to check or assess whether the baby's intelligence is normal or if there are any issues? Which hospitals can address my concerns (I live in Taoyuan County)? Can infants have their IQ tested? Or do you have any better suggestions regarding my worries and concerns? Please provide detailed answers, Dr.
Pei.
Wishing you health, peace, and smoothness.

Feichang danxin erzi de mama, 20~29 year old female. Ask Date: 2006/04/07

Dr. Pei Rensheng reply Pediatrics

Hello! From the detailed records, it is clear that you are very attentive to your baby's growth and development.
Here is an overview of congenital hypothyroidism: 1.
According to the Department of Health, the incidence is approximately 1 in 2,800.
Most cases are due to underdevelopment of the newborn's thyroid gland, leading to a deficiency of thyroid hormones.
Symptoms typically begin to appear between two to three months and may include lethargy, a low nasal bridge, dry skin and hair, a hoarse cry, umbilical hernia, abdominal distension, constipation, an enlarged tongue, difficulty breathing and feeding, persistent jaundice, and growth and developmental delays.
If treatment is administered within the first one to two months after birth, both growth and IQ can develop normally.
However, if treatment is delayed until after six months, most children will experience cognitive impairment and growth delays.
Due to the gradual onset of symptoms, early diagnosis was previously challenging, but current screening methods are essential for early detection.
If the screening results are normal and your baby is two months old without any of the aforementioned symptoms, there is no need for concern.
2.
As I understand, a two-month-old infant cannot have their IQ quantified numerically, but you can refer to the developmental milestones in the health booklet to observe if your baby is lagging behind.
Additionally, during your baby's check-up at one month and 18 days, their weight was 5,600 grams (75-90th percentile), height was 56.5 cm (50-75th percentile), and head circumference was 37.5 cm (25-50th percentile), which does not suggest congenital hypothyroidism (the typical presentation is that weight and height are delayed while head circumference is slightly larger; this is the opposite of your baby’s measurements).
3.
Prolonged breastfeeding can benefit your baby's cognitive development; if possible, breastfeeding can continue until your baby is over one year old (remember to introduce complementary foods after six months).
4.
There are no reports in the literature indicating that discontinuing medication during pregnancy adversely affects the infant's cognitive abilities.
5.
For concerns regarding IQ or developmental issues, you may consult a pediatric neurologist, such as Dr.
Chang Chao-Liang from Taoyuan Hospital, whose clinic hours are Wednesday afternoons, Friday mornings, and Monday afternoons (by appointment).
Sincerely, Pei Ren-Sheng.

Reply Date: 2006/04/07

More Info

Thyroid dysfunction during pregnancy, particularly hypothyroidism, can have significant implications for both maternal health and fetal development. It is understandable that you have concerns regarding the potential impact of your thyroid condition on your newborn's intelligence and overall growth. Let's address your questions systematically.

1. Impact of Missing Medication on Fetal Intelligence: It is known that untreated or inadequately treated hypothyroidism during pregnancy can lead to adverse outcomes, including potential cognitive impairments in the child. However, the extent of this impact often depends on the severity and duration of the hypothyroid state. Since you resumed your medication and your newborn's thyroid function tests came back normal, it is a positive sign. The fact that your obstetrician noted normal growth parameters during pregnancy also suggests that your baby may not be adversely affected.
2. Birth Weight and Growth Parameters: Your baby was born at a healthy weight and size, which is a reassuring indicator. The absence of signs of congenital hypothyroidism, such as low birth weight or developmental delays, further supports the notion that your child's growth and development are on track. While there is always a possibility of subtle cognitive effects, the current evidence suggests that your child is developing normally.

3. Indicators of Cognitive Function: Your husband's assertion that cognitive issues are often accompanied by growth delays is generally accurate. However, your child's growth metrics indicate that he is thriving. The normal results from the brain ultrasound are also encouraging. Cognitive development can be assessed through various milestones, and your child's current abilities, such as responding to sounds and smiling, are positive signs of normal neurological development.

4. Developmental Milestones: At nearly two months, your baby’s ability to respond to stimuli and exhibit social behaviors is a good sign of cognitive engagement. These early milestones are crucial indicators of healthy brain development. Continued monitoring of developmental milestones will provide further reassurance as your child grows.

5. Breastfeeding and Cognitive Development: Breastfeeding has been associated with numerous benefits, including potential positive effects on cognitive development. While it may not "reverse" any potential impacts from your thyroid condition, providing breast milk can support overall health and development. It is advisable to continue breastfeeding as long as possible, as it provides essential nutrients and antibodies.

6. Assessing Infant Intelligence: Currently, there are no standardized tests for measuring IQ in infants. Pediatricians typically assess developmental progress through regular check-ups, focusing on milestones in motor skills, language, and social interaction. If you have concerns, you can discuss them with your pediatrician, who may refer you to a specialist if needed.

In summary, while your concerns are valid, the current indicators suggest that your child is developing well. Regular pediatric check-ups will help monitor your child's growth and development, and any concerns can be addressed promptly. If you are still worried, consider consulting a pediatric neurologist or a developmental specialist for further evaluation. Your proactive approach to your child's health is commendable, and maintaining open communication with your healthcare providers will ensure the best outcomes for your family.

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