Twins and triplets are often a welcome surprise for parents who want big families, but these bigger bundles of joy are pricey. A new study finds that extra costs begin mounting from conception for mothers expecting multiple births.

The findings, published in the American Journal of Obstetrics & Gynecology, raise the question of whether these families should receive hospital discounts for their care.

The twinning rate has witnessed a precipitous 76 percent rise since 1980, according to the Centers for Disease Control and Prevention, as reproductive technologies such as ovulation induction and in vitro fertilization (IVF) have become more popular. But more than half — 60 percent — of all twin birth are still the result of natural conception. The authors of the study argue that higher costs of care for multiple births may institute an unfair burden for families who did not use IVF, and therefore, weren’t necessarily expecting twins or triplets.

To create cost comparisons between twin and singleton pregnancies, the researchers mined information from the Truven Health MarketScan Commercial Claims and Encounters Database, an independent source of comparative healthcare data. Of the 437,000 births, 12,000 were twins, while 560 were triplets or more.

They examined documents for 437,000 birth events, analyzing the medical expenses during pregnancy for the mothers from 27 weeks gestation to 30 days after delivery. Medical costs for the children through the first year of life were also added to the tallies.

The adjusted total cost of healthcare was $21,000 per delivery with singletons, $105,000 with twins, and over $400,000 with triplets or more.

“By taking a broad approach, we have shown that medical expenses attributable to mothers and infants varied according to birth multiplicity,” lead investigator Dr. Dongmu Zhang of Global Health Outcomes, Merck & Co, said in a statement

Zhang and his colleagues found much of this cost was due to mothers with twins or multiplets having pre-existing conditions or developing illnesses during this timeframe. Mothers with twins or more had significantly higher rates of hypertension, cardiovascular disease, diabetes, edema/renal disease, genitourinary infection, thyroid disease, anemia, and conditions in the reproductive tract.

“On average, combined all-cause healthcare expenses for mothers with twins or higher-order multiple births were about five to 20 times more expensive, respectively, than singleton delivery,” Zhang said. “The greater expenses were likely to have been due to increased maternal morbidities, significantly increased use of cesarean section and longer hospital stay for the deliveries in women with multiple pregnancies; and increased admission and longer stay in NICU for neonates of multiple gestations.”

The authors claim this is the first study to record increased medical expenses for both maternal and infant care associated with IVF-assisted pregnancy. They suggest that IVF strategies should be revised to prevent the transfer of multiple embryos, which would ultimately reduce the likelihood of twin and multiplet pregnancies.

Lemos EV, Zhang D, Van Voorhis BJ, Hu H. Healthcare expenses associated with multiple vs singleton pregnancies in the United States. American Journal of Obstetrics & Gynecology. 2013.