As a first-time parent, you will never forget that very first ultrasound visit. I certainly wont. Thats when the technician pointed out two blob-like shapes when we were expecting only one.

Youre having twins, she said.

I suddenly saw our future: Double the sleepless nights. Twice the number of bottles to wash. My modest salary doubly stretched to pay for the incalculable amount of diapers, baby food and bibsall stamped with that inescapable, red devils face: Elmo. (Its Elmos world, all right; we just live in it.)

But, I did not see what was coming next. At 23 weeks along, we went for another ultrasound. As the tech looked at the sonogram, she became very quiet. She excused herself to find our OB/GYN, who then took a serious look at the ultrasound images.

Within two hours, we were at Childrens Hospital of Philadelphia, and our little blob-like shapes were now under the care of a fetal cardiologist. Baby B, looked fine, but an echocardiogram showed that Baby A had supraventricular tachycardia, or SVT. Translation: The upper chambers of the babys heart were beating much faster than the lower chambersso fast that, before long, the heart wouldnt be able to supply enough oxygenated blood. If the SVT continued, Baby A would not survive. And, if one fetus died, chances were good that the other wouldnt make it, either.

My wife, Karin, spent the next 10 days, including July 4, in the hospital. The fetal cardiologists explained that antiarrhythmic drugs were needed. There was no direct way to get the drugs to the fetus, so Karin had to take them. The drug therapy was a careful balancing act: The drugs had to pack enough punch to knock down the SVT in Baby A but not be too powerful to adversely affect Baby B or Karin.

First, they tried digoxin. Didnt work. They added sotalol, and Baby As heart rate dropped. But, now it was too lowabout 80bpm and erratic. They tinkered with the dose. Finally, Baby As heart rate reached a stable, relatively normal plateau. Fortunately, Baby B seemed unaffected.

In late July, Karin was readmitted when her EKG was abnormal. The doctors stopped the sotalol, and within 24 hours, Baby As heart rate had skyrocketed again. They restarted the sotalol. More tinkering with the dose. Over Labor Day weekend, Karin went back into the hospital. More tinkering.

By September 17, the drugs began to affect Baby Bs heart rate. It was five weeks before the due date, but it was time to deliver. A few hours, a few anesthetics, and one cesarean section later, we were the proud but extremely tired parents of Mary Jane (Baby A) and Elizabeth (Baby B).

That was more than two years ago. Mary Jane continued to take digoxin and amiodarone until her first birthday. The SVT hasnt returned.

We are still extremely tired.

My point: You cant be too careful when prescribing medications for pregnant and nursing women, infants and children. In this months Optometric Study Center, Topical Treatment in Our Most Vulnerable Patients, Drs. Mary Bartuccio, Rachel Coulter and Marc Taub enumerate the various ways that topical ophthalmic drugsthough largely safe in most adultscan pose significant harm to these particularly vulnerable populations. As this article explains, doctors must carefully consider the needs of both the mother and child.

So, before prescribing a steroid, dont hesitate to ask a young woman if shes pregnant or nursing. And, before giving a baby gift, consider if the poor, tired parents really want yet another lousy talking Elmo toy.

(Amy Hellems Editors Page returns next month.)