The Zohar HaKadosh calls Psalm 20 the Song of the Woman in Labor.
The psalm’s 70 words correspond to the 70 cries of a woman in labor—the 70th cry is when she gives birth.
Psalm 20 consists of 9 pesukim (verses), not including the introductory verse, corresponding to the 9 months of pregnancy. This psalm contains exactly 70 words, and each of these words represents one of the types of cries a woman utters when giving birth (according to Kabbalah, the child is born specifically as a result of these 70 types of cries).
It is well known that a painful pregnancy and difficult labor are punishment for the woman for the Original Sin—for following the serpent’s advice.
The earliest Midrash in the world, "Pirkei De-Rabbi Eliezer" , states that the true tempter of Adam and Chava was not even the serpent itself, but Satan, who entered into it. Moreover, the Shlah HaKadosh offers an interesting allusion to this: it turns out that Satan and Nachash (the serpent) are nearly equal in gematria (numerical value): שטן = נחש, and the fact that the gematria of שטן is greater by 1 (359), according to the Maharal of Prague, indicates that it was Satan who exerted the influence.
All of this also parallels the state of the Jewish people before the Exodus from Egypt and the state in which we find ourselves today—"Chevlei Mashiach" (the birth pangs preceding the coming of Mashiach).
Segulot 1) Pregnant women should recite Psalm 20 daily. The pasuk corresponding to the month of pregnancy (the 2nd month, the 3rd, and so on) should be recited 3 times; In the 9th month, the 9th pasuk (not counting the introductory verse) is recited three times; 2) According to Rabbanit Batsheva Kanievsky (zt"l), this psalm should be recited 20 times.(Based on a lesson on Zohar on Pinchas, by Rav Tzvi Nisanzon, using material from Toldot.ru)
