Since then, Tony has been officially diagnosed with autism. Years of speech, occupational and behavioral therapy have helped him progress to the point where he can attend a mainstream kindergarten class for part of the day, albeit with a one-on-one aide and special education classes for all of his academics.

A lithe, cheerful, brown-haired boy who strips down to his boxers the moment he gets home from school and always walks around the house on tippy-toes, Tony can tell his parents what he wants but can't manage a typical chat.

"We don't have back-and-forth conversation," Russo said. "'Mommy, I want juice. Mommy, I want goldfish [crackers] a pink bowl.' He's very anal and specific."

So much so that when Russo set an after-school snack on the coffee table for Tony one recent afternoon, he promptly rearranged it. He needs his juice, for some reason, to sit to the left of his goldfish.

Tony is a very advanced reader. He once used alphabet puzzle pieces to instruct his father, Darryl, as he struggled to fix a computer, to "follow directions." But he thinks so literally that when he first read what was on the fire alarm at kindergarten, he did what it said: "Pull." Fire trucks were summoned and the whole school had to evacuate.

"He has a very literal mind," his mother said. "He doesn't think about consequences."

The challenges of raising one autistic child were enough to lead Russo to quit her job, a few months after his diagnosis, as an executive assistant at her father's insurance business. The prospect of having a second is even more daunting.

"In the beginning [of her second pregnancy], I wasn't worried," Russo said. "I don't know if it was hormones or what. 'Oh, we'll be fine.'"

Russo said her "mommy gut" told her early on that the baby she's expecting was girl. She was hoping for a girl because boys are four times more likely to have autism. But she started worrying that it might be a boy as her ultrasound appointment approached.

"I didn't even want to go to the ultrasound," she said. "I really went through a month of total freak-out. If we had another exactly like my son, yeah, we know how to deal with it. What if we had a child who was more severe?"

Ultimately, she went to the ultrasound and learned she was having a girl, which helped her relax again.

Of course, she knows there is still a chance that her daughter will be on the autism spectrum, which is why she welcomes the expert evaluations the girl will get through the study.

Having researchers come look at the cleaning products in her home or inquire if the pineapple she ate was canned, fresh, organic or conventional has certainly made her wonder if there are things she could be doing to improve her daughter's chances of avoiding autism. But outside of trading Mop & Glo for a homemade floor cleaner made with vinegar and baking soda and buying natural shampoo for Tony, she has not changed how she lives.

"I wouldn't doubt it if there is something in houses or in the air that causes it, but I'm not sure if we're close enough to knowing," she said. "We all buy our cleaning supplies, disposable diapers, all the things we come in contact with — we don't even think about that they're not natural. They're made with chemicals."

Having read something online about a possible association between delivery-room drugs and autism — "I know just enough to be dangerous," Russo said with a laugh — she will try to have a natural childbirth this time. She is considering hiring a doula to help her accomplish that.

The EARLI study is just one of several active autism research studies currently recruiting families. Landa and Kennedy Krieger are also studying toddlers who are late talkers, baby siblings of children with autism, pre-term infants, and typically developing infants and toddlers.

But Landa urges families not to pass up on the opportunity to enroll in the EARLI study, something mothers can do up to their 28th week of pregnancy.

"This is sort of the study, OK, in terms of causes of autism," Landa said. "It's not the kind of thing like Macy's has a sale every month for some special event. 'Oh, you know, I'm going to pass on this.' Every single family counts."

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