By on October 21, 2015

The birthrate for twins has increased substantially in this country over the past 35 years. Doctors are trying to find ways to improve outcomes for women with twin pregnancies. Dr. Nathan Fox, father of twins himself, discusses management of twins, as well as recent research on twin pregnancies published along with his colleagues at Maternal Fetal Medicine Associates .

The main reason for an increase in twin pregnancies is women availing themselves of assisted reproductive technologies, such as IVF. Also, the average age of women who become pregnant in this country has increased over the past 30 years; the older a woman is, the rate of twining naturally increases as well. Those two factors, mainly IVF, have increased the rate of twins significantly in this country.

Tools to Help Twin Pregnancy Births

For twin pregnancies, there are several increased risks compared to women carrying one baby. The biggest risk is preterm labor and preterm birth. This has significant health consequences for those babies throughout life. Here at Maternal Fetal Medicine Associates, we developed a new diagnostic tool to help women who are pregnant with twins. This tool helps calculate the risk of preterm birth in twin pregnancies using established clinical and laboratory tests.. One test is an ultrasound that measures the length of the cervix. The cervix is the bottom of the uterus (the womb) where the baby is held. . If you measure the length of the cervix by ultrasound, the longer the cervix, the lower the risk of preterm birth and the shorter the cervix, the higher the risk of preterm birth. The second test is called fetal fibronectin, which is abbreviated as fFN. For test we do a Q-tip swab of the vagina then send it to a lab for testing. We then see if it gives us a positive (bad) or negative (good) result. If you get a positive result, your risk of preterm birth increases.

We have been using these tests in twin pregnancies for many years and we’ve compiled and published our data into a user-friendly format. This way, for a patient with a twijn pregnancy, if she undergoes these simple tests, her doctor (or the patient herself) can calculate her risk of a preterm birth.

How Twin Pregnancy Tests Work

Let’s say Dr. Fox is seeing a patient that is 24 weeks pregnant, which is about six months. He measures her cervix and it is 13 millimeters, which is short. Her fetal fibronectin test is positive. If you go to our website,, you will find our twin calculator. Here you can plug in 24 weeks, 13 millimeters, fetal fibronectin positive. The results will tell you that she’s likely to deliver around 31 weeks, which is quite early. The calculator will give you the percent chance of delivery prior to each week. This is very important information for these women and their doctors to know how high risk she is for delivering early.

Is there any way to prevent that premature birth?

When Dr. Fox presents his data and research at national meetings, this is the question that the researchers and doctors ask the most: “What can we actually do?” Unfortunately, there’s very little in what we can currently do to prevent preterm birth in twins or prolong pregnancy. The preventative measuress that we have, such as bed rest, medications, and hospitalization have not been shown to be helpful. So you may be thinking, “If there’s really nothing you can do to prevent preterm birth, why are you doing all these tests?”

However, even though we can’t prevent preterm birth as well as we would like, there are things we can do to prepare before preterm birth that can improve the health outcome for the babies. For example, let’s say we have two women who have twins and are both going to deliver at 31 weeks. But, one of whom I have predicted in advance that she is going to deliver early. The other patient shows up at 31 weeks in labor and delivers without warning. The babies of the first patient are going to do better. The reason is that there are medications we can give to women before they deliver, like steroids, magnesium or antibiotics, which have been proven to improve the health of the premature babies. This is the main reason we use these tests.

In one of our published studies, we have compared twins in our practice, for whom we do these tests, to twins in another large academic center, where they don’t do these tests routinely. As expected, the twins delivered at the same time, meaning that using these tests didn’t make our patients stay pregnant longer. However, we found that women with twins in our practice who delivered less than 34 weeks (which is when steroids are indicated) had better rates of steroid administration, as well as improved timing of these steroids (closer to delivery).

There is a lot of discussion about medicine: whether it is or is not worth it. Much of the discussion that comes into play is whether it’s worth potentially scaring someone unnecessarily. This means that we could have someone who tests positive for this, but doesn’t deliver early and then maybe we scared her without cause. We are weighing that risk against the potential benefit of being prepared for a preterm birth.

At Maternal Fetal Medicine Associates in New York, the way we take care of twin pregnancies is comprehensive. We don’t just take these tests and say, “Okay, you’re positive, everything’s horrible, and give them these medications, and scare them to death.” But we talk to them and say, “Okay, your risk went from this to this, let’s make a decision. Do we want to give the steroids now? Do we want to wait? Do we want to check again in a few days and see what happens?” We use these tests to help women and guide them to have overall lower stress levels for their pregnancy. The most important thing, of course, is to improve the outcomes for their babies – this is our number one priority!

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Maternal Fetal Medicine blogs are intended for educational purposes only and do not replace certified professional care. Medical conditions vary and change frequently. Please ask your doctor any questions you may have regarding your condition to receive a proper diagnosis or risk analysis. Thank you!