Statistics on the prevalence of Irish twin births in the United States are lacking. However, extremely short birth intervals are relatively uncommon. One study found that 35% of subsequent pregnancies were conceived within 18 months of a prior birth, which is over two years apart or less between births. Typically, Irish twins are conceived within just 3 months of a prior birth. Longer intervals from previous childbirth to conception are possible if the subsequent child is born prematurely. While the typical definition of Irish twins is two children spaced 12 or fewer months apart, people do sometimes use the term more loosely to include children born 13, 14, or more months apart, particularly if the children end up in the same grade in school. Learn more about Irish twins, including the history of the term and the potential advantages and challenges of having two children spaced closely together.

History of Irish Twins

The phrase “Irish twins” originated in the late 19th century as a disparaging term associated with Irish immigration to the United States. The implication was that groups of close-in-age siblings were a negative characteristic of large Irish Catholic families. In fact, it was common for Irish immigrants to have children close in age because they followed the Church’s strict guidelines regarding contraception. Back then, when the phrase was used, the person was stereotyping the Irish and implying that they were uneducated, poor, and lacked self-control. However, you need to be cautious when using this term, as “Irish twins” is not only slang but also disparages Irish culture and can be offensive—even if you are using it affectionately. It’s more appropriate to simply recognize that the children are closely spaced siblings or close-in-age siblings or to say nothing at all about their ages.

Types of Twins

When people refer to Irish twins, it’s important to recognize that although the siblings are close in age, they are not actually twins. In other words, they were not born during the same gestational period. Calling them Irish twins is just an informal way of classifying siblings that are born close together. Twins are two children born from the same conception, carried during the same pregnancy, and born together, either on the same day or a day or so apart. The main types are fraternal twins (dizygotic twins), which form from two separate eggs fertilized by two separate sperm, and identical twins (monozygotic twins), which form from a single (mono) fertilized egg (zygote). So, Irish twins aren’t twins as they are born months apart from different pregnancies. The exception is if you’re referring to twins born in Ireland at the same time to the same mother. They are true Irish twins that are twins in the technical sense.

Potential Challenges

There are a variety of challenges that may come along with closely spaced births, including greater risks of adverse physical and mental health impacts for both the baby and parents. There also may be increased financial costs due to needing to care for two small children at once, a reality that also tends to keep parents out of the workforce for longer. Divorce rates increase, as well. However, the influence of these factors varies greatly from family to family. According to a 2014 study on the impacts of having closely spaced children, “Short interpregnancy intervals are associated with a number of adverse outcomes for both mother and child, including increased risk of preterm birth, low birth weight, and preeclampsia, making prevention of short interpregnancy intervals a public health priority in the United States.”

Potential Advantages

While there are known risks of having children spaced closely together, there are also many potential benefits. For some families, spacing their babies one after the other is a goal and they enjoy having their kids grow up close in age. They may feel it will give their children a greater bond and let the family focus on one stage at a time. Plus, they can reuse or share many items, such as clothing, toys, and bottles. Some people may want to have many children or are having children later in life, so they choose to reduce the time span between pregnancies. Other people may just want to let pregnancy happen whenever it occurs naturally, whether that means spaced closely together or farther apart. Ultimately, only you know what the optimal spacing plan is for your children—although sometimes, pregnancies happen regardless of our plans.

Tips for Parenting Irish Twins

Parenting is challenging, and it can be even more so when you’re trying to raise two kids so close in age. Here are some tips to help make it easier.

Ask for Help

Especially during the baby and toddler phase, raising two kids close in age can feel overwhelming at times. Don’t be afraid to ask for help, whether that means splitting child and household responsibilities with your partner or hiring outside help.

Create a Routine

Solid sleep and eating schedules can be lifesaving for you and your little ones. Not only will it help keep things organized, but it will also allow you to schedule in some much-needed “me” time.

Don’t Compare

Every child grows and develops differently, and that includes children born within 12 months of each other. So, remember not to compare or expect them to be the same.

Encourage Individuality

Irish twins can be very competitive, so it’s important for parents to recognize their individuality. As they grow older, encourage them to have separate activities and hobbies so they can get a break from one another and have their own outlet to shine.

Practice Self-Care

Even when you feel like you don’t have a single second to devote to yourself, it’s important to set aside time for self-care. Taking care of your spiritual, physical, psychological, and social needs will help you feel your best so you can be the best parent to Irish twins you can be.

Raising Irish Twins vs. Fraternal or Identical Twins

Although the challenges of parenting Irish twins are different from having fraternal or identical twins, there are many issues that may be similar to what parents of twins face: One big difference is that with Irish twins you have a newborn and an older baby to take care of while parents of twins have two babies at the exact same age simultaneously. Additionally, actual twins are born from one pregnancy, while Irish twins are born from two, which takes a different toll on the body of the pregnant person. However, there are also big similarities, including:

Double the supplies: With Irish twins, you’ll have two children in diapers at the same time, two cribs, two high chairs, and the need for a double stroller.Simultaneous schedules: Sometimes, closely spaced children can end up in the same grade at school. They may have the same friends, enjoy the same activities, and generally live a similar lifestyle as they grow older, much in the way that twins would.Shared celebrations: Their birthdays may be close enough that your family celebrates them together.

Arguably, the experience is more diverse with younger children. For instance, a newborn and an 11-month-old baby have vastly different developmental capabilities. Meanwhile, a 9-year-old and a soon-to-be 10-year-old may not appear quite so distinct. As puberty approaches, the differences may become more pronounced again for a while, then less distinguishable as the children grow up.

A Word From Verywell

Having children close together can be a choice that some families make. Or, it may be that the pregnancy was unexpected. Either way, when you don’t know the circumstances or are with people you don’t know well, you may want to refrain from discussing the situation or pointing it out. There may be some personal issues regarding the spacing of the children that a family would prefer to keep private or they may find the term offensive.