Medical Researcher Consulting Notes
10 February 2016

New Study Increases Concern Of Zofran’s Pregnancy Safety

Over 220 Zofran lawsuits are now consolidated in Boston, according to docket records at the US District Court of Massachusetts. Filed by families from across the country, each suit accuses GlaxoSmithKline, one of the world’s largest pharmaceutical manufacturers, of concealing evidence that its popular anti-nausea drug can cause birth defects.

As evidence of the link, parents have thus far relied on 3 major studies, conducted between 2013 and 2014, that all found an increased risk for birth defects among children exposed to Zofran during the first trimester of pregnancy. The studies suggest that the drug’s active ingredient, a chemical called ondansetron, makes it more likely for an unborn child to develop cleft palate and congenital heart defects.

Boston University Study Finds New Evidence Of Birth Defect Risks

But a new lawsuit, filed directly in the US District Court of Massachusetts on February 2, 2016, makes use of even more recent research. Registered under the case number 1:16-cv-10153-FDS, the lawsuit (PDF) notes an entirely new study – one that “show[s] elevated risk ratios for cardiac malformations.”

Researcher Preparing Study

The study in question has not yet been formally published, although its results were presented at a conference for the International Society of Pharmacoepidemiology (ISP) held between August 23 and 26, 2015 in Boston.

Sponsored by Harvard’s T.H. Chan School of Public Health and Boston University’s Slone Epidemiology Center, the annual conference focuses on studies investigating the side effects of drugs. Many of the world’s most prominent birth defect researchers convene in Boston every year, to announce new research results. This year, a group led by Samantha E. Parker, an epidemiologist at Boston University, presented the results of their analysis “Ondansetron for the Treatment of Nausea and Vomiting of Pregnancy and the Risk of Birth Defects.”

An abstract describing the study’s methods and conclusions can be found here.

Multiple Data Sources Consulted

Hoping to investigate ondansetron’s potential effect on fetal development, Parker and her co-authors looked at a variety of records. Maternal interviews and pregnancy records were gathered from the Slone Birth Defects Study, which compares the medical histories of healthy babies to those of babies born with birth defects. Data also came from the National Birth Defects Prevention Study, an initiative of the US Centers for Disease Control & Prevention (CDC).

The researchers focused their analysis on women who had been prescribed Zofran during the first trimester. Just beginning to form, fetal tissues are believed to be more susceptible to harmful chemicals at this time.

Increases In Heart, Kidney & Diaphragm Defects

In the data from Slone, the researchers identified 243 pregnancies exposed to the drug’s active ingredient. 111 women from the CDC’s records had been prescribed ondansetron during the first trimester. That’s not a lot, at least where medical research is concerned, and the relatively small patient pool considered may limit the scope of conclusions that can be drawn from the study. Be that as it may, the researchers found that babies exposed to Zofran during early pregnancy were:

  • 2.3 times more likely to be born with renal atresia
  • 50% more likely to be born with hypoplastic left heart syndrome
  • 70% more likely to be born with diaphragmatic hernia

The study also noted a “modestly elevated” incidence of cleft palate. Women prescribed Zofran were 50% more likely to deliver children with cleft palate, a birth defect that a different study found was more than twice as likely among babies exposed to Zofran during the first trimester. It’s interesting to note that both papers used data from the National Birth Defects Prevention Study to arrive at their results. Marlene Anderka, director of the Massachusetts Center for Birth Defects Research and Prevention, played a role in conducting both studies.

The authors were quick to hedge their results. Noting that few of the pregnancies studied actually involved Zofran exposure, the researchers characterized their estimates as “unstable.” Despite the uncertainty of its conclusions, the study struck a cautionary tone in its final statement: “given the current widespread use of ondansetron, further studies of its safety are needed” [emphasis added].

Renal Atresia

More commonly referred to as renal “agenesis,” babies born with renal atresia are missing a kidney. “Atresia” itself refers to any organ or passageway in the body that is either absent or abnormally closed. Most forms of atresia are congenital – present at birth. Children can be born missing either one or both kidneys. In the former instance, the condition is properly called unilateral renal agenesis. The latter abnormality is known as bilateral renal agenesis.

Renal agenesis is relatively. The unilateral form affects between 1 in 450 and 1 in 1,000 births every year according to HealthLine. About 1 in 3,000 babies are born missing both kidneys. While children born with bilateral renal agenesis cannot survive, and will live for only hours after delivery, babies born with a single kidney may never experience any ill effects.

Hypoplastic Left Heart Syndrome

Hypoplastic left heart syndrome, or HLHS, is a complex abnormality in which the left side of a child’s heart fails to develop completely. In some children, the organ’s left ventricle, which usually pumps oxygen-rich blood out to the body, may be entirely absent. Whether missing or present, but underdeveloped, the chamber is unable to supply the body’s organs and tissues with an adequate supply of blood for survival.

Most babies with HLHS require a series of open heart surgeries. Even after these procedures, which help with proper blood flow, it’s likely that affected children will face lifelong complications.

Several families have already filed lawsuits claiming Zofran caused their child to be born with HLHS. You can learn more about one of these cases, filed by a mother from Birmingham, Alabama, here. Strikingly, the mother also claims her child was born with a kidney defect, although she does not specify the nature of this condition.

Diaphragmatic Hernia

The diaphragm is a large muscle that sits between the chest and abdomen. When the diaphragm contracts, the chest expands, drawing air into the lungs. Babies born with diaphragmatic hernia have an opening in this muscle, a hole that allows organs in the belly to poke through and press against the lungs.

As a result, children with the condition almost always develop breathing problems shortly after birth. The diaphragm itself is often unable to move properly, and requires immediate surgery.