Newborns face some critical adaptations when they are born and start to breathe on their own.
During the last seven months of pregnancy, an unborn human child has a functioning bloodstream without, of course, functioning lungs. The fetus can't gasp for breath when her oxygen levels go low. To compensate for the necessity of extracting oxygen from the mother's bloodstream after it has passed by other organs, unborn babies have a high-potency oxygen-binding form of the protein known as fetal hemoglobin, or HbF.
This form of hemoglobin is very effective for binding to oxygen so it the fetus gets all the oxygen it needs from the mother's blood. It's not as effective at releasing that oxygen into the baby's bloodstream. Nor does it have to be. A baby in the womb isn't going to go snow skiing at high altitude or join a pickup basketball game.
When the child is born, however, fetal hemoglobin becomes potentially problematic. The baby has to breathe on his own, but fetal hemoglobin is slow to release oxygen to the cells that need it. As long as the baby's blood contains mostly fetal hemoglobin, it needs more hemoglobin. When the neonate's body begins to produce an "adult" form of hemoglobin known as Hb (or Hgb). Before the baby's body has replaced HbF with Hb, it needs high hemoglobin, at least 12 grams per deciliter, to function properly. After the baby's body has replaced HbF with Hb, it only needs 6 grams per deciliter to function normally. Not every baby, however, matures so anemia can be avoided even when hemoglobin levels fall.
Hereditary Persistence of Fetal Hemoglobin
Some people, however, lack a genetic "control switch" called BCL11A. This gene is responsible for stopping the production of "baby hemoglobin" HbF and starting the production of adult hemoglobin Hb. 
What kinds of complications can arise from having HbF that persists beyond infancy? Most authorities will tell you that hereditary persistence of hemoglobin in and of itself is a benign condition. High fetal hemoglobin levels delay the symptoms of sickle cell disease in infants and toddlers . Physicians sometimes even give sickle cell patients medications that deactivate BCL11A so they will have more energy because their blood carries more oxygen . Adults who suffer oxygen deprivation at high altitudes adapt to the stress by producing more HbF . But persistence of high hemoglobin levels isn't always a good thing. Certain kinds of kidney tumors in children are associated with high, persistent levels of fetal hemoglobin . If the body needs greater oxygen-carrying capacity in its hemoglobin after birth (if you spend time at high altitude, for instance, or you develop heart disease), it can restart the creation of HbF . But you can also help the production of adult hemoglobin along by making sure of one simple element of nutrition for your baby.
Zinc and HbF Hemoglobin Production
The part of the BCL11A gene that can fail to function, so it does not activate the production of adult hemoglobin, is known as its "zinc finger. " Babies whose mothers had zinc-deficient diets during pregnancy sometimes can't activate this gene, but people later in life who have full-blown hemoglobin disorders like beta-thalassemia and sickle cell disease sometimes suffer zinc-deficiency, too . Zinc supplements aren't enough to activate a mutant gene, but they will help a normal gene perform its intended function .
If you are breastfeeding, the best way to make sure baby gets enough zinc is for the mother to get enough zinc . You can do this by taking supplements, but there's no need to overdose. Just 10 mg a day is enough, and 15 mg a day is tolerable, although 30 mg a day should be your upper limit. Too much zinc depletes copper. It's also possible to get all the zinc you need from zinc-rich foods. Spinach doesn't have the most zinc of all the foods, but it's especially easy to work into your diet. Beef is rich in zinc, as are blackcurrants, pumpkin seeds, wheat germ, and almonds.
There's a very easy way to determine whether you need to take zinc. Place a zinc tablet on your tongue and let it dissolve. If your reaction is "eww," it has a metallic taste, you don't need the supplement. But if you do, take up to 30 mg a day so you can pass the mineral on to your baby in breast milk. You will also be giving your child greater immunity against childhood diseases  and a healthier start on life.