Quadruplets are a multiple pregnancy where a woman carries and gives birth to four babies. These occurrences are rare. Quadruplet births can result from biological factors or modern medical interventions.
Statistical Overview of Quadruplet Births
Quadruplet births are numerically uncommon, representing a very small fraction of all live births. In 2022, only 121 quadruplet births occurred in the United States, highlighting their rarity compared to over 100,000 twin births. Historically, their natural occurrence is estimated at 1 in 512,000 to 1 in 700,000 pregnancies. This natural incidence follows Hellin’s Rule, describing a mathematical relationship between single and higher-order multiple births.
Multiple birth rates have changed. From 1980 to 1998, triplet and higher-order multiple birth rates increased fivefold. From 1998 to 2023, these rates, including quadruplets, declined by 62%. Quadruplet and higher-order births specifically decreased by 79% in the U.S.
Factors Influencing Quadruplet Conception
Natural biological factors can increase the likelihood of conceiving quadruplets. Advanced maternal age, typically over 35, is one factor; as women age, hormonal changes like increased follicle-stimulating hormone (FSH) can lead to the release of multiple eggs during ovulation, raising the chance of a multiple pregnancy. Genetics also plays a role, with a family history of fraternal multiples, especially on the mother’s side, indicating a tendency for hyperovulation where more than one egg is released. This increases the probability of conceiving fraternal quadruplets. Previous pregnancies, particularly multiple pregnancies, may also slightly increase future chances.
The Impact of Medical Advancements
Modern medical advancements, especially Assisted Reproductive Technologies (ART), influence multiple birth frequency, including quadruplets. IVF and ovulation-inducing medications are primary contributors. These technologies increase pregnancy chances by stimulating egg production or transferring multiple embryos, potentially leading to multiple gestations.
Fertility drugs like clomiphene citrate can increase twin chances by 5-12% and triplets by less than 1%. Stronger injectable medications, such as gonadotropins, can result in a 30% twin pregnancy rate and a 5% chance of triplets or more. In 2011, ART was associated with an estimated 78% of all triplet and higher-order births.
The practice of transferring multiple embryos during IVF historically contributed to higher rates of multiple pregnancies. However, due to concerns about the health risks for both mothers and babies, clinical guidelines have shifted. Fertility clinics now often recommend transferring fewer embryos, sometimes even a single embryo, to reduce the incidence of multiples while still achieving a successful pregnancy. This change has contributed to the recent decline in higher-order multiple birth rates.