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Reassuring Developmental Results for Children Born after ART

Data about development. In 2013, a large review of more than 80 studies concluded that more data were still needed to truly understand whether or not fertility treatments had an impact on children’s outcomes.¹

Although previous studies hadn’t shown a difference in the cognitive development of children born after use of ART, results for motor development were deficient or conflicting. But the biggest remaining question had centered on language development. By addressing shortcomings of previous research, a recent prospective study may have helped to lay some of this controversy to rest.²

New prospective study. Publishing their results in the February issue of Obstetrics & Gynecology, researchers compared children born following ART with children born after natural conception. The paper was entitled “Neurodevelopmental Outcomes After Assisted Reproductive Technologies.” From a total of 2,366 pregnant women, 2,088 pregnancies had occurred after natural conception and 278 children had been conceived using ART. Assisted reproductive technologies included:

• Ovarian stimulation—using medication to encourage the ovaries to select and release more eggs than usual
• Intrauterine insemination—placing sperm inside a woman’s uterus to aid fertilization
• IVF (IVF)—fertilizing an egg outside the body and then placing the embryo in the uterus.
• Intracytoplasmic sperm injection—injecting a single sperm directly into an egg
• In vitro maturation (IVM)—using less medication to stimulate the ovaries than with standard IVF and taking eggs before they are mature, maturing and fertilizing them to create an embryo, and placing the embryo in the uterus.

Neurodevelopmental assessments. Nearly 63 percent of the children in the ART group and about 64 percent of the children in the natural conception group underwent neurodevelopmental assessments 24 months after birth. The researchers used standardized and validated tools to compare the children’s language, motor, and cognitive development. These tools were the Bayley Scales of Infant and Toddler Development, 3^rd edition, and the MacArthur-Bates Communicative Development Inventories.

The MacArthur-Bates Communicative Development Inventories is a parent questionnaire. For this study, the researchers used a 100-word vocabulary production checklist and a question about early word combinations.

The Bayley Scales includes 5 independent scales, which are made up of a series of developmental play tasks. For this study, the researchers used the cognitive and motor scales. The cognitive scale assesses functions such as:

• Memory
• Exploration
• Manipulation
• Sensorimotor development (the coordination of sensory experiences such as sights and sounds with motor aspects of bodily activity)

The motor scale, which is divided into fine and gross motor tasks, evaluates:

• Quality of movement
• Sensory integration (the ability to take in, organize, and process information from the senses for use)
• Perceptual-motor integration (the ability of different sensory systems to work together)
• Prehension (the ability to grasp or seize)
• Other milestones

Adjusting for potential bias. The researchers first accounted for other factors, such as parental age, family income, maternal ethnicity, education, or history of smoking or depression. These are considered potential confounders—factors that can lead to bias by distorting the magnitude of the results. For example, patients in the ART group tended to be older and more educated than those in the natural conception group. Therefore, the researchers took this into account to prevent bias in the study results.

Results: no differences between groups. Comparing the ART and natural conception groups, the researchers found no differences:

• In Bayley scales’ cognitive scores
• In MacArthur-Bates language scores
• In composite motor skills
• When comparing independent ART techniques (although the study was not powered to detect these differences)
• When comparing in vitro techniques such as IVF or IVM with other techniques such as ovarian stimulation or insemination

Of course it’s always possible that differences in development might show up after age 2. But for many prospective parents undergoing IVF or other types of ART, these results are very reassuring.

Sources

1. Bay B et al. Fertility and Sterility.2013:100:844–853.
2. Balayla J et al. Obstetrics & Gynecology.2017;129(2):265–272.

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