Albert Einstein and Mileva Maric have daughter Lieserl
In early 1902, Einstein and Mileva Marić had a daughter they called Lieserl in their correspondence, who was born in Novi Sad where the parents of Mileva lived. Her full name is not known, and her fate is uncertain after 1903.
Lieserl (born January, 1902 – last mentioned in 1903; date of death unknown) was the first child of Mileva Marić and Albert Einstein.
According to the correspondence between her parents, "Lieserl" was born in January, 1902, a year before her parents married, in Novi Sad, Vojvodina, present day Republic of Serbia, and was cared for by her mother for a short time while Einstein worked in Switzerland before Marić joined him there without the child.
"Lieserl's" existence was unknown to biographers until 1986, when a batch of letters between Albert and Mileva was discovered by Hans Albert Einstein's daughter Evelyn.
Marić had hoped for a girl, while Einstein would have preferred a boy. In their letters, they called the unborn child "Lieserl", when reffering to a girl, or "Hanserl", if a boy. Both "Lieserl" and "Hanserl" are diminutives of the very common german names Liese (Elisabeth) and Hans (Johannes).
The first reference to Marić's pregnancy is found in a letter Einstein wrote to her from Winterthur, probably on May 28, 1901 (letter 36), asking twice about "the boy" and "our little son", whereas Marić's first reference is found in her letter of November 13, 1901 (letter 43) from Stein am Rhein, in which she refers to the unborn child as "Lieserl". Einstein goes along with Marić's wish for a daughter, and refers to the unborn child as "Lieserl" as well, but with a sense of humour as in letter 45 of December 12, 1901 "... and be happy about our Lieserl, whom I secretly (so Dollie  doesn't notice) prefer to imagine a Hanserl."
The child must have been born shortly before February 4, 1902, when Einstein wrote: "... now you see that it really is a Lieserl, just as you'd wished. Is she healthy and does she cry properly? [...] I love her so much and don't even know her yet!"
The last time "Lieserl" is mentioned in their extant correspondence is in Einstein's letter of September 19, 1903 (letter 54), in which he shows concern for her suffering from scarlet fever. His asking "as what is the child registered? [Adding] we must take precautions that problems don't arise for her later" may indicate the intention to give the child up for adoption.
Private Einstein letters fell into the hands of the public in the 80ies and caused a lot of sensation, because they revealed that Einstein had an illegitimate daughter with his former fellow student Mileva Maric.
Mileva gave birth to a daughter at her parents’ home in Novi Sad. This was at the end of January, 1902 when Einstein was in Berne. It can be assumed from the content of the letters that birth was difficult. The girl was probably christianised. Her official first name is unknown. In the letters received only the name “Lieserl” can be found.
The further life of Lieserl is even today not totally clear. Michele Zackheim concludes in her book “Einstein’s daughter” that Lieserl was mentally challenged when she was born and lived with Mileva’s family. Furthermore she is convinced that Lieserl died as a result of an infection with scarlet fever in September 1903. From the letters mentioned above it can also be assumed that Lieserl was put up for adoption after her birth.
In a letter from Einstein to Mileva from September 19, 1903, Lieserl was mentioned for the last time. After that nobody knows anything about Lieserl Einstein-Maric.
The reasons why Albert Einstein and Mileva Maric didn’t take her daughter in after her birth won’t be explained here in any more detail.
Even today there is no sign that Albert Einstein has ever seen his daughter.