When the daughter of the Persian king Darius III Codomannus (ruled 336-330) was born, she was called Barsine. She was probably born in 340 or 339, as we will see below.
Barsine's father's reign was an unhappy one. In 334, the Macedonian king Alexander invaded the Achaemenid empire, and he defeated Darius in the battle of Issus (November 333; more). Among the captives were Darius' mother Sisygambis, his wife Statira, his five year old son Ochus, and two daughters, Barsine and Drypetis. The Macedonian conqueror treated them kindly, which was not an act of courtesy but a claim to the Persian throne: in the ancient Near East, a new king would take over the wives of his predecessor (full story).
In the negotiations before the battle of Gaugamela, Darius offered Barsine to Alexander as his bride, adding as her dowry all country west of the Euphrates. Alexander refused, saying that he knew that her father had already promised the girl to his general Mazaeus. The real reason may have been another one: he had started an affair with Barsine's mother Statira. Alexander's biographer Plutarch of Chaeronea tells us that Alexander, "esteeming it more kingly to govern himself than to conquer his enemies",note[Plutarch, Alexander 21.7.] sought no intimacy with Darius' wife. This is not true: Statira was captured in November 333 and died in childbirth in September 331. Darius cannot have been the father of the baby.
After the battle of Gaugamela (1 October 331), Alexander occupied Babylonia, Elam, and Persia. Barsine and Drypetis were left behind in the capital of Elam, Susa, to be educated as Macedonian girls. Seven or eight months later, they learned that their father had been killed by his courtiers (text).
In March 324, Barsine married to Alexander, the man who was responsible for her father's death; at the same time, her sister Drypetis married to Alexander's closest friend Hephaestion (text). It was probably on this occasion that Barsine received her new name, Statira - like her deceased mother, who had been her husband's former lover. At the same time, Alexander married to Parysatis, the daughter of the former Persian king Artaxerxes III Ochus.
In 328, Statira's fiancé Mazaeus had died, without marrying the woman he was supposed to marry. This can only mean that Statira had not reached the minimum age to marry in 328, thirteen, which in turn suggests that she was born after 341. However, she and her younger sister must have been thirteen years old in 324. If this argument is sound, Statira was born in, say, 340-338 and Drypetis in 339-337. This means they were 5-7 and 4-6 when they were captured after the battle of Issus. Since we know for sure that their brother Ochus was at that moment five years old, we may assume that Statira was born in 340/339 and Drypetis in 338/337.
After the death of Alexander (11 June 323), his first wife Roxane and his successor Perdiccas, saw to the murder of Statira. This suggests strongly that she was pregnant, because otherwise, she would not have been a threat to Roxane.