I've written a lot of articles on the subject of raising bilingual children, but for new parents, this may be my most important post yet.
First, though, let me say that this warning won't necessarily apply to everyone - after all, the makeup, and circumstances, of every family are uniquely different. Those fortunate to have a fair amount of exposure to the minority language in their setting, such as situations where the child has access to schooling in that language, will probably not share this concern to the same extent. Also, parents who plan to introduce a second language when the child is older - cases of "successive bilingualism," in other words - are pursuing a different sort of path. This message, then, is directed to parents much like myself:
You dream of bringing up your children in both languages simultaneously, from birth - "simultaneous bilingualism" - so you can hand down your language heritage from the earliest age and communicate with them in your mother tongue throughout their childhood.
At the same time, your setting itself offers limited exposure to the minority language and your children will likely attend a local school and be educated in the majority language. This means that, essentially, you are the main source of exposure to the minority language - and, to make this even more challenging, you might not be the main caregiver.
If you're a new parent, and this sounds at all familiar, I urge you to heed the warning that follows and share it far and wide with other parents.
Hit the ground running
First and foremost: Do not assume this will be easy. If you suppose that your child will simply "pick up" the minority language from you, this could be a fatal mistake.
While no one has ever died of a failed attempt at bilingualism, it's certainly true that the dreams of many parents have been dashed because they realized too late that raising a bilingual child demands a lot more time, energy, and expense than they originally imagined.
The truth is, if you want your children to gain their two languages simultaneously, and yet their exposure to the minority language rests mainly on your small shoulders, you must hit the ground running. The bilingual journey is a marathon, it's true - and you can't burn yourself out early on - but if you begin too slowly from the starting line, you'll fall behind fast.
The first few years of a child's life, when so much language development is brewing inside that little brain, are absolutely crucial when it comes to your success. If the odds are against you, in terms of your circumstances, you must shift them in your favor by being proactive and doing everything in your power so that, from day one, your child is exposed to the minority language roughly 25 hours a week.
The scale of your dream
The hard reality is this: If there isn't sufficient exposure in the minority language, its development will rapidly fall behind the relentless progress of the majority language. Then, before you know it, the child is three or four and the majority language is already much stronger and has become the child's main means of communication. You abruptly realize that your aim of simultaneous bilingualism, where the child communicates with roughly equal ease in both languages, isn't taking shape as you had hoped.
At that point, you're forced to play "catch up" with the minority language, which requires even greater effort - and may not be possible if you're unable to make significant changes to your lifestyle in order to rebalance the child's language exposure. To avoid this predicament - and the dashed dream that could follow - it's far better to start strong and make steady efforts so that the minority language can "keep pace" with the majority language.
Again, this warning will not apply to all. And there's nothing wrong, of course, with resetting your expectations when you find that your original goal is beyond your capacity.
But if it's important to you - truly important to you - that your child acquire both languages simultaneously so that you can communicate in your mother tongue for the life of your relationship, then you must be mindful of the actual size of this challenge and make certain that your efforts match the scale of your dream.